Hi, we have the below license that allows for 27 users (18+9) for Business Central On-Premise (with enhancement plan)

Is it possible to understand when this user limit is enforced, please? Is 27 the number of concurrent users (i.e. 27 users can have an open session at the same time)? Or does this mean that I can have 27 enabled users in the users list?
Any help is appreciated.
Thanks in advance!