It can be difficult to determine the meaning of a sentence outside of any kind of context. The sentence "He smiled at her winningly, but I don't think she was fooled by him" is a good example of that. The reader has no clue as to why she should have been fooled by him or if he was trying to fool her.
"He graduated from college at a young age" means that the person the person was younger than a typical college graduate when he graduated. (Am I missing something?)