"I'm sorry for being later." is correct, but I guess you mean "I'm sorry for being late.". "I'm sorry for late" is incorrect. You can either say "I'm sorry for <verb>." or "I'm sorry for <noun>." In noun form, you can say: "I'm sorry for my lateness." In verb form, it's <verb>ing, which is why you can say: "I'm sorry for being late." Or you can say "I'm sorry that I am late." Some other examples are: "I'm sorry for moaning." [verb] "I'm sorry for the delay." [noun] "I'm sorry for what I said."