If your friends describe you as saintlike, they mean that you're pretty much perfect. Someone who's saintlike always seems kindhearted and good, no matter what.
You can also use the word saintly to describe people whose kindness and virtue you deeply admire. Both adjectives essentially mean "like a saint," so you can call your incredibly patient teacher saintlike, or talk about your saintlike next door neighbor, who never complains about your barking dog and loud music. Saintlike and saint have a Latin root that means "holy."