When we talk about something being a matter of opinion, it means that people can have different views and thoughts about it. Let's take ice cream as an example - some people may think that vanilla ice cream is the best, while others may prefer chocolate or strawberry. There is no right or wrong answer because everyone has their own preferences.
Now, in some cases, opinions can be based on facts or evidence. For instance, it is a fact that smoking is harmful to health, and most people would agree with that statement. However, there may be some people who believe that smoking is not that bad or that the risks are overstated. This is still an opinion, even though it goes against the scientific evidence.
So, to summarize, when we say that something is a matter of opinion, it means that people can have different thoughts and ideas about it, and there is no one right answer. It is important to respect other people's opinions, even if we don't agree with them.