Setting permissions in a process is a means of designating who can map and run a process.
When you are mapping a process you will see the permissions options in the process properties panel on the right hand side of your diagram canvas.
Setting process permissions
You can choose to set process permissions for either Run or Map. That could be the same process permissions for each option or different for each option, depending on what access you want user roles to have.
User roles with Run permission will be able to select and start this process
User roles with Map permission will be able to edit, save, and publish this process
When you select either Run or Map permissions you will be given a dropdown list of user roles to choose from. Simply select the user role you want to give process permissions and it will be added!