You don't know what that means? All this is telling you is that you need to use your left hand in the treble clef. Pick up a theory book sometime

This is a solo piano sheet music… the bottom line in a score written for piano is always left hand, no matter what the clef

No. No No No No No No No.No. No No No No No No No.No. No No No No No No No.No. No No No No No No No.No. No No No No No No No.No. No No No No No No No.No. No No No No No No No.No. No No No No No No No.No. No No No No No No No.No. No No No No No No No.

Pro pianist here, I can explain, even though this was made about when my account was made
It could be because of a clef change in the music, such as bring the left hand up into the treble or crossing hands. It could also just be a screw-up on the composers part, and they just accidentally put the bass clef there.

Here’s the thing this is the first line. It’s not s clef change it’s literally the first line. I believe this was Mozart Piano Sonata K545

Well then it's either the composer's fault or the fault of whoever re-wrote it