If i am asked to dicuss the niche of brine shrimp what does that mean please help!!?

That means: talk about the role that brine shrimp play in the scheme of something like the food chain or the ocean's biology. So... if you were asked that in science, and you've been studying the food chain, then, you'd talk about brine shrimp in terms of what they eat + what eats them + what eats that, and so on. If you had to talk about them in some other context, think of their "role" (for niche) and their function in that position (food, etc.).