What does the German word Niche mean?

Niche is not a German word. It is derived from the French word niche (recess), which in turn comes from the Latin nidus, meaning nest.

The word means:

a shallow recess, especially one in a wall to display an ornament.

a comfortable or suitable position in life.

a specialized but profitable corner of the market.

Ecology a role taken by a type of organism within its community.