Is a the word bumble bee a pronoun?

No, the Word bumble bee is a noun, a singular, common, compound, concrete noun; a Word for an insect; a Word for a thing.

A pronoun is a Word that takes the place of a noun in a sentence. The pronoun that takes the place of the noun bumble bee is it for the singular, they for a plural subject and them for a plural object of a sentence or clause. Examples:

A bumble bee was busy on a branch of Apple blossoms. It moved from flower to flower carrying the pollen with it.

Some bumble bees were busy on a branch of Apple blossoms. They moved from flower to flower carrying the pollen with them.