The A0-C2 levels you have heard about are CEFR levels.
CEFR: Common European Framework of Reference.
In Belgium they usually follow a different level system.
A0: You know literally nothing, A0 is nothing.
A1: You can introduce yourself with some mistakes and you understand a little when people are speaking slowly and you focus. You can also pick up the subject and key details from fliers or short newspaper articles. There is no Belgian equivalent to this level.
A2: You can introduce yourself with almost no mistakes. You can also talk about yourself, your family, day to day life, but with mistakes, while searching for words. You are struggling conversational. The past tense is probably a bit rusty sometimes. You can read most newspapers, but you struggle a little with vocabulary. In Belgium they call this level 1F.
B1: You can talk about day to day life with little to no mistakes, but you still lack some advanced grammar and vocabulary. Officially you are ‘able’ to work in this language, but you will probably suffer from imposter syndrome, because B1 is not enough to feel comfortable working in, every day all day. One or 2 meetings a day, sure though. Most native Dutch resources are written in B1, so you will be able to read the newspaper without much trouble. You just need to look up some really specific vocab occasionally. In Belgium they call this level 2F.
B2: You are getting professional. You can work in this language and you will probably feel comfortable most of the time. You still make mistakes sometimes, but every now and again, some people mistake you for a native speaker. B2 is the level of lower educated natives, though you will probably not make the same types of mistakes they will make. In Belgium they call this level 3F.
C1: This is a fully professional level. You will be able to read Dutch literature without any difficulties. You can do a job interview in this language without worrying about the language, only worrying about the content of the conversation. In Belgium they call this level 4F.
C2: This is the highest reachable level. It is comparable to a native speaker who studied a bachelor’s in that language.
So, I’m Dutch, and then let’s say I have a bachelor’s degree in the Dutch language, that is C2.
C2 is also the level you need to write a Master’s or PhD thesis in that language, without worrying about the language, only the content. There is no Belgian equivalent to this level, just 4F+.
Also, There are no specified grammar topics that are necessarily one level or the next. It is all about being able to use/consume the language in certain fluency and context.