Why does Citra doesnt have sav slots like other emulators?

It will be a real help

Savestates haven’t been implemented yet. Search the forums for a detailed answer as this question has been asked and answered several times. I’ll give a gist here:

Savestates require saving the entire state of the emulator, and recalling them later. While it may sound not-so-hard in theory, it’s quite difficult in practice. The reasons for this are highly technical & I’m not sure I understand them properly. So I won’t try to explain them. (Can any visiting developer help here?)

You need to save in-game. Some games do provide the functionality within the game itself. You can use that just fine.