Question

There are many fanciful floats in the parade. What is the subject

Answer 1

The subject of this setence would be floats because that is what the sentence is talking about

Answer 2

The subject in this sentence is "many fanciful floats".

The structure of "there is/ there are" sentences is the following:

There+ verb to be+ subject

The sentence can havea  singular subject ("There is a cat in my coach", where "cat" is the subject) or it can have a plural subject ("There are many cats in my coach", where "many cats" is the subject).