Shōnen-ai is a word that comes from Japan, and it refers to a type of story where two male characters have a romantic relationship. Imagine if you have two boy friends, and they like each other more than just being friends, and they hug and kiss like in a fairy tale.
These stories usually have a lot of emotions, and they are made for people who like romance, but particularly for people who like the idea of two boys together. But don't worry, it's not a bad thing! Everyone has different tastes, and there's nothing wrong with liking something that others might find strange.
The word shōnen-ai is often used to describe anime or manga (Japanese comics) that have this type of story. Some people like watching or reading shōnen-ai because it shows that love is not just between a boy and a girl; it can be between any two people, and that's okay.
In summary, shōnen-ai is a type of story where two male characters have a romantic relationship. It's just like any other love story, but the main characters are both boys. It's not a bad thing, and it's okay to like it if it makes you happy.