The Accelerated Data Science (ADS) SDK is an Oracle-developed Python library that makes common data science tasks faster, easier, and less error prone. The ADS SDK provides tools for data ingestion, exploration, transformation, visualization, modeling, evaluation, interpretation, and deployment. The ADS SDK also integrates with other popular Python libraries such as pandas, scikit-learn, TensorFlow, PyTorch, etc.
The ADS SDK is included as part of the Data Science service at no additional cost. The Data Science service is a fully managed platform that enables data scientists to build, train, deploy, and manage machine learning models on OCI. The Data Science service provides access to notebook sessions that come pre-installed with the ADS SDK and other essential Python packages for data science workflows.

For more information on Oracle Cloud Infrastructure Free Tier refer below official documentation
https://docs.cloud.oracle.com/en-us/iaas/Content/FreeTier/freetier.htm?Highlight=Free%20Tier Exadata DB Systems aren't a part of the free tier:

Oracle Cloud Infrastructure offers best-in-class security technology and operational processes to secure its enterprise cloud services. However, for you to securely run your workloads in Oracle Cloud Infrastructure, you must be aware of your security and compliance responsibilities. By design, Oracle provides security of cloud infrastructure and operations (cloud operator access controls, infrastructure security patching, and so on), and you are responsible for securely configuring your cloud resources. Security in the cloud is a shared responsibility between you and Oracle.
In a shared, multi-tenant compute environment, Oracle is responsible for the security of the underlying cloud infrastructure (such as data-center facilities, and hardware and software systems) and you are responsible for securing your workloads and configuring your services (such as compute, network, storage, and database) securely.
In a fully isolated, single-tenant, bare metal server with no Oracle software on it, your responsibility increases as you bring the entire software stack (operating systems and above) on which you deploy your applications. In this environment, you are responsible for securing your workloads, and configuring your services (compute, network, storage, database) securely, and ensuring that the software components that you run on the bare metal servers are configured, deployed, and managed securely.
More specifically, your and Oracle's responsibilities can be divided into the following areas:
Identity and Access Management (IAM): As with all Oracle cloud services, you should protect your cloud access credentials and set up individual user accounts. You are responsible for managing and reviewing access for your own employee accounts and for all activities that occur under your tenancy. Oracle is responsible for providing effective IAM services such as identity management, authentication, authorization, and auditing.
Workload Security: You are responsible for protecting and securing the operating system and application layers of your compute instances from attacks and compromises. This protection includes patching applications and operating systems, operating system configuration, and protection against malware and network attacks. Oracle is responsible for providing secure images that are hardened and have the latest patches. Also, Oracle makes it simple for you to bring the same third-party security solutions that you use today.
Data Classification and Compliance: You are responsible for correctly classifying and labeling your data and meeting any compliance obligations. Also, you are responsible for auditing your solutions to ensure that they meet your compliance obligations.
Host Infrastructure Security: You are responsible for securely configuring and managing your compute (virtual hosts, containers), storage (object, local storage, block volumes), and platform (database configuration) services. Oracle has a shared responsibility with you to ensure that the service is optimally configured and secured. This responsibility includes hypervisor security and the configuration of the permissions and network access controls required to ensure that hosts can communicate correctly and that devices are able to attach or mount the correct storage devices.
Network Security: You are responsible for securely configuring network elements such as virtual networking, load balancing, DNS, and gateways. Oracle is responsible for providing a secure network infrastructure.
Client and Endpoint Protection: Your enterprise uses various hardware and software systems, such as mobile devices and browsers, to access your cloud resources. You are responsible for securing all clients and endpoints that you allow to access Oracle Cloud Infrastructure services.
Physical Security: Oracle is responsible for protecting the global infrastructure that runs all of the services offered in Oracle Cloud Infrastructure. This infrastructure consists of the hardware, software, networking, and facilities that run Oracle Cloud Infrastructure services.
Reference:
https://www.oracle.com/a/ocom/docs/oracle-cloud-infrastructure-security-architecture.pdf