My left scrotum is longer than the right side n vein like structure inside i can felt . what is the problem ?

Likely, varicocele..: What described could indicate having a prominent varicocele above left testis, which commonly occurs in some 15% of men of various degree. If yes, yours is a big one so being called like a bag of worms, but most of times it still needs no active care except few concerning infertility and symptoms. More? Seek confirmation/ counseling by urologists timely. Best wish to health...