Question

What is it called when two or more words in a line have the same sound?

Answer 1

A Homophone

Answer 2

thanks

Answer 3

Actually, I am 99% certain that it is known as alliteration. A homophone is a word that sounds like another, but means and is spelled differently.
For example:

Homophone: Bye, Buy, By
Alliteration: Peter Piper Picked a Peck of Pickled Peppers.

Homophones are different words, but sound the same.
Alliteration is two or more words in a sentence that start or end with the same sounds.