At time of writing, the current version of Photoshop 2023 (desktop) is 25.0 and the current version of Photoshop on the iPad is 5.0.
Adobe is constantly updating its software so these numbers will change over time. But really, you don't need to know what the latest version number is.Because Photoshop is made available through subscription via the Creative Cloud, you can always access the most up-to-date version of the software.
That's worth doing because it means you'll benefit from the latest new features, updates to existing features and performance enhancements. To update your software, you just need to launch Photoshop and choose Help > Updates from the menu.