How bad is a muscle contusion. and what exactly is it.?

Well i went to the doctor and he said i had a muscle contusion and a possible torn tended or something anyway it not in the bicep or tricep . he is a really good doctor, but i don't remember what all he said. Anyway I had x-rays done and everything. So how bad is a muscle contusion and what exactly is it. all i know is it was painful enough to make my mom think it was broke. sorry for my horrible grammar