A prepositional phrase is a group of words that can be placed in either subject or object position. They normally begin with a preposition plus a noun which is the object of the preposition. In this sentence, the prepositional phrase is (on the team) being ON the preposision and THE TEAM the noun. The main function of preposition is to connect the elements in a sentence.
For example:
They run in the park.
In the park is a prepositional phrase.
In is the preposition
The park is the object of the preposition.