I've heard some people from Belgium say they speak Flemish though, I'm aware that it's Dutch but I say Flemish just because of the people who I've encountered from the region who refer to it as such, or Flemish Dutch. The way I understand it the differences are somewhat analogous to British and American English, where of course it's the same language but with pronunciation differences and a few words that are different, like "biscuits" vs "cookies", etc. Maybe that's an oversimplification and I need to talk to more people from the region before making jokes about it. Also some Belgians are even trilingual, must be fun. I'm trying to get there, but my parents opted not to teach me my native language growing up and I'm being really lazy about learning Japanese, even with the motivation of watching anime and playing eroge without translations. At least I had a good French teacher in high school, so I'm almost there lol.