How come you can't taste things when you don't breathe through your nose?

How does breathing have anything to do with tasting. Does smelling activate our taste buds or something?

Nope. It is because much of what we think of as a food’s “taste” is actually it’s smell. Smell is the major component of most flavor. The taste buds on the tongue are only capable of detecting sweetness, saltiness, sourness, and bitterness (and maybe “meatiness”) and combinations thereof. The nose can detect hundreds of distinct smells.