What is the difference between a "dual-band" and regular 2.4ghz wireless router?

I just bought a Belikin Router that was recommended to me because it’s a Dual-Band router. In fact, it says “simultaneous dual band.” is that something you have to manually set up? is it something that is not generally needed at all? or is it an automatic feature that will enhance my wireless experience noticeably? does anyone know? lol Thanks!