Some people say that we're born with certain abilities. Others say that abilities are developed through experiences. Probably both of these ideas are true, but it is definitely true that each of us has abilities. And for each of us, some abilities are stronger than other ones. When you answer that question, you're talking about your abilities.
People are usually happiest when they have the chance to do the things they do well.
If you're in school, this means taking the courses in which you do your best. If you're working, it means having a job that uses as many of your abilities as possible. Thinking about what you do well leads to choices in school and to careers that can make you happier. Think about what you do well. If you ask people who know you to tell you what your abilities are, they might be able to tell you.