Roles are used to control access to applications and modules in the application navigator. Each application menu or module has a role field that specifies which role is required to view it. Users who do not have the specified role or a role that contains it will not see the application menu or module. Roles can also be used to control access to other features and capabilities in ServiceNow, such as tables, fields, scripts, and workflows.
Reference = Enable or disable an application menu or module, Grant a role access to applications and modules, Controlling access to applications and modules.

Explanation
Explanation/Reference: https://community.servicenow.com/community?
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It is best practice to define the business requirements and the process(es) an application will manage as part of the application development plan. The following are some of the considerations to document as part of the business process:
Business problem. This is the description of the problem or opportunity that the application is intended to address or exploit. It should include the background, context, scope, and objectives of the problem or opportunity.
Data input/output. This is the specification of the data that the application will need to collect, store, manipulate, and display. It should include the data sources, formats, validations, transformations, and integrations of the data.
Users/stakeholders. This is the identification of the users and stakeholders who will be involved in or affected by the application. It should include the roles, responsibilities, expectations, and needs of the users and stakeholders.
Process steps. This is the definition of the steps and activities that the application will perform or support. It should include the inputs, outputs, triggers, conditions, and outcomes of each step or activity.
The following are not some of the considerations to document as part of the business process:
Project schedule. This is the estimation of the time and resources required to complete the application development project. It should include the milestones, deliverables, dependencies, and risks of the project. This is not part of the business process, but part of the project management plan.
Database capacity. This is the measurement of the amount of data that the application will generate and store in the database. It should include the data volume, growth rate, retention policy, and backup strategy of the data. This is not part of the business process, but part of the technical design and architecture of the application.
Available licenses. This is the number and type of licenses that the application will consume or require from the ServiceNow platform. It should include the license model, cost, and allocation of the licenses. This is not part of the business process, but part of the financial and legal aspects of the application. References: Application Development Process, Business Process Analysis