Is this a mattress pad or a topper?

It is a pillow-top mattress pad. It adds a soft cotton cushioning layer over the mattress rather than the deep foam lift of a topper.

Will it make a firm mattress softer?

It softens the surface and adds light cushioning. Sleepers wanting real pressure relief on a very hard mattress usually need a thicker foam or latex topper.

Does the cotton top sleep cool?

A cotton top breathes better than polyester or down-alternative pads, so it stays cooler for hot sleepers. The loft underneath still traps some warmth.

Cotton tops are generally machine washable on a gentle cycle and should be line dried or tumble dried low to limit shrinking. Follow the care label on the pad.

Does it fit a standard queen mattress?

It is made for queen-size mattresses. Check the pad's skirt depth against your mattress height before buying, especially with a thick mattress or a mattress plus topper.