Deals access allows you to use Pipedrive's core sales functionality. By having access to Deals, you will have access to your pipeline, leads, deals, contacts, and all related features. Within Deals, users are assigned visibility groups and permission sets to control what they can see and do in the account.
Any user with Management access can assign Deals access to other users. To do this, go to Company settings > Manage users. You can then click on the three dots (...) beside the user you would like to give deals access to.
When granting a user to deals access, you will have to put them under a permission set of either Admin user, Regular user, or if you are on professional or enterprise plan, managers.
Admin users— Admin users have access to all of the deals, contacts, and features in the account. They also have the ability to:
Regular users— A Regular User is the default name for users who are not an Admin User, or not within another permission set in Pipedrive. Regular users have Deals access and can use the core functionality in Pipedrive. Based on the chosen options in that permission set, the user may have limited access to viewing and changing certain items in the Pipedrive account.
Managers— If you are on Pipedrive's Professional or Enterprise plans, you have additional permission sets. The Manager permission set gives you an extra set so that you can give some users more permission within the account without allowing them full visibility within the account. Users on the Professional plan will have the manager permission, and users on the Enterprise plan can create unlimited additional custom sets.
For more information on permission sets in Pipedrive, you can read this article. You can regulate what deals or contacts they can view or what features they can view by editing their visibility groups.