Explanation
Account teams are groups of users who work together on an account. You can enable account teams in Setup and assign team roles and access levels for each team member. Users can set up a default account team that is automatically added to any account that they own or create. This makes it easier for teams to collaborate with the same customer without manually sharing each account. References:
https://help.salesforce.com/s/articleView?id=sf.accountteam.htm&type=5
https://help.salesforce.com/s/articleView?id=sf.accountteam_default.htm&type=5

Explanation
The Knowledge Lightning component is a component that allows users to access articles fromthe Service Cloud Console app. However, if users want to access articles from a different app that does not use the console, they can use the Knowledge related list instead. The Knowledge related list shows articles related to a record based on data categories and shows article details such as title, summary, rating, and view count. To add the Knowledge related list to a record page, an administrator can use the page layout editor and drag and drop the Knowledge related list to the appropriate section on the page layout. References:
https://help.salesforce.com/s/articleView?id=sf.knowledge_lightning_component.htm&type=5https://help.salesfo

Explanation
A restricted picklist is a type of picklist that enforces the integrity of the picklist values by allowing only values defined inthe picklist during data entry or import operations. If the restricted picklist checkbox is checked for a picklist field, then any records with values not defined in the picklist will cause errors during import operations. However, if the restricted picklist checkbox is unchecked for a picklist field, then any records with values not defined in the picklist will be imported without errors.
References:https://help.salesforce.com/s/articleView?id=sf.picklist_limitations.htm&type=5