Complex sentence: Flemings speak Dutch (specifically its southern variant, which is sometimes colloquially called'Flemish') which is the majority language in Belgium, being spoken natively by three-fifths of the population.
Split into simpler sentences: Flemings speak Dutch (specifically its southern variant, which is sometimes colloquially called'Flemish'). It is the majority language in Belgium, being spoken natively by three-fifths of the population.