I didn't have my period yet. so i always get these cramps at my left ovary. i get it everyday. what is it?

The internal abdominal organs do not have localizing nerve endings that would allow one to point to a single origin like an ovary for pain. At best you could say it localizes to a single region but it could be intestinal/bladder or other nearby organ. You identify a source by having an exam and testing if needed. The symptom description is not specific to a single label/dx/rx.