The Flemish Parliament is the representative body of the Flemish people. It represents both the Flemish Community (language, culture, education, welfare) and the Flemish Region (economy, environment, mobility, housing). The Parliament votes on decrees, which are the laws that apply in Flanders. It approves the Flemish budget, which means it decides where tax money is spent.
It also keeps an eye on the Flemish Government (the ministers). Members of Parliament can ask questions or call minister. (Source: https://www.vlaamsparlement.be/nl)