Describe something you do every day that you enjoy.
If you have several things you enjoy, what is the commonality between them?
If you can't think of anything, then consider activities you do every day or on most days or weeks. Even if you are not sure if you enjoy them, there may be something you do that suggests enjoyment.
Once you have an idea or a notion, consider what it has in common with other things. For instance, if you like counting numbers, finding patterns in them, and shifting them about to create complex equations, you may have math proficiencies that can help you indicate what you are good at. If you like animals and pets and taking care of them, then you might have aptitude in fields that deal with animals. If you happen to be creative, what creative things do you enjoy?
You do not need to be "good at" anything however. some people are good at several things, but not to any great degree, some have one thing above all others they are good at, and some have interests that aren't things that offer excellence in the world at large. It is hard to tell without some input or feedback from you to know about these things. Being "good at" a thing isn't necessary for having ASD, or even for being NT. Many NT people aren't good at anything. And many are good at things that do not help them in life. Same goes for people on the spectrum. I am one of those...I am good at several things, but none of them are useful day to day. I am competent in one specific field, but I really do not enjoy it at all.