Explanation
Page layout editor is a tool that allows you to customize the layout and organization of detail and edit pages for a specific object and record type combination. You can use page layout editor to make fields editable or read-only on page layouts for different profiles or record types. After resetting a password, the user may be required to activate their device by entering a verification code sent to their email address or phone number before they can log in to Salesforce. This is a security feature that helps prevent unauthorized access to Salesforce from unknown devices or browsers. References:
https://help.salesforce.com/s/articleView?id=sf.customize_layoutedit.htm&type=5
https://help.salesforce.com/s/articleView?id=sf.identity_verification.htm&type=5

A gauge component shows a single value along with its percentage of a total value within predefined rangesusing colors (red-yellow-green). It is useful for showing key performance indicators (KPIs) such as total sales amount and progress towards sales goal.
References:https://help.salesforce.com/s/articleView?id=sf.dashboards_gauge_component_type.htm&type=5

Explanation
One possible reason why a manager receives an error when trying to approve a record is that the user in the next approver step is inactive or missing, which means there is no valid user to assign the record to after approval. To troubleshoot this issue, an administrator should check if the user in the next approver step is active and exists in Salesforce; if not, they should activate or create the user or change the approval process to assign the record to another user. Adding a delegated approver for the next approver in the process does not solve this issue because delegated approvers are only used when approvers are unavailable; they do not replace approvers who are inactive or missing. Updating the field level security to view on fields that are updated in the process does not solve this issue because field level security does not affect approval processes; it only affects what fields users can see or edit on page layouts. Reviewing the page layout to ensure fields updated in the process are visible does not solve this issue because page layouts do not affect approval processes; they only affect what fields users can see or edit on page layouts. References:
https://help.salesforce.com/s/articleView?id=sf.approvals_considerations.htm&type=5

Explanation
To show different picklist values for sales and marketing users, you can either use record types or profiles.
Record types allow you to have different picklist values for different page layouts assigned to different profiles. Profiles allow you to restrict picklist values based on user permissions.
References: https://help.salesforce.com/s/articleView?id=sf.customize_recordtype.htm&type=5
https://help.salesforce.com/s/articleView?id=sf.admin_profile_picklists.htm&type=5

Explanation
An external ID is a custom field that has the external ID attribute enabled, which means it can beused as an identifier when importing and updating records from an external system. It allows administrators to match records based on a unique ID value from another system instead of using Salesforce record IDs, which may not be available or consistent across systems. An auto-number field is a custom field that automatically assigns a unique numeric value to each record, but it cannot be used as an identifier when importing and updating records from an external system because it is generated by Salesforceand may not match with the external system's IDs. A rich text field is a custom field that allows users to enter formatted text, images, and links, but it cannot be used as an identifier when importing and updating records from an external system because it is not unique or consistent across systems. A record ID is an internal ID assigned by Salesforce to each record, but it cannot be used as an identifier when importing and updating records from an external system because it may not be available or consistent across systems.
References:https://help.salesforce.com/s/articleView?id=sf.custom_field_attributes.htm&type=5