Net neutrality is the current state of the internet (or before the FCC repealed it anyway). With net neutrality, network provides are NOT allowed to charge additional money or block their users from seeing certain website domains.
Example: Without net neutrality, Comcast can slow down or block att.com, because it may help their marketing. They could also charge the user to use att.com.
With net neutrality, this is not allowed. It keeps the internet equal and fair for everyone who may use it.