Yes, PS 12 was basically the version for 2018-2019. Last school year PowerSchool announced a new numerbing system to 19.4 is 2019 April's release.
You should review the release notes. The biggest changes in 19 are to password management, the "look" of PS, the versioning and teachers can now transfer assignment grades when they have a student drop one of their classes.
New to PT Pro - V 19:
The Insider episodes that Jason Springel does (and which are posted to PowerSource) are very helpful.
Release Notes on PowerSource: