Dainty means tiny, delicate, and lovely, so you could describe a little china tea set as dainty, and you could also call the tiny cakes on the little plates dainty.
The original meaning of dainty, back in the 1300s, was "choice morsel of food," and it's still used that way to talk about a delicacy or a treat. More often, dainty is used as an adjective to describe something that's delicate and lovely. It's a compliment, unless it's used sarcastically to mean "someone who acts ridiculously prissy." An example would be to say, "Sorry I hurt you when I barely brushed against you. I didn't realize you were so dainty."