Okay kiddo, so you know how sometimes people have different ideas about things? Like how you might think vanilla ice cream is the best but your friend might think chocolate is the best? Well, that's kind of like a matter of opinion!
Opinions are like ideas or thoughts that people have about things - and they can be different from person to person. For example, some people might love the color pink, but to others it just doesn't seem very pretty.
This is why some things can be called a matter of opinion. It means that different people might have different thoughts or ideas about what they like or don't like, or what is good or bad.
It's important to remember that these different opinions are okay - just because someone likes something different than you, it doesn't make their opinion wrong or bad. We all like different things and that's what makes life interesting!