What is a Profile?
Through Profile, object and application access could be managed.
Is Admin: This user will have admin access of particular instance.
Object permission: This is to manage object level permissions
Read: user has read permissions for the records that one owns.
Create: user can create records in the objects.
Update: user can update the owned records in the objects.
Delete: user can delete the owned records in the objects.
Erase: user can permanently delete the owned records in the objects.
Read All: user can read all records of a particular object.
Modify All: user can modify (Update, Delete, Read, Erase, Read All) all the records in object.
Field Permissions: This is to manage the field level permissions.
Visible: user can read and update the field value.
Read only: user has read only permission for particular field.
Feature permissions
License permissions