Irrelevant material/redundancies are unnecessary words that add nothing new to your sentence and make it wordy.
Explanation:
I'm assuming you mean redundancies by "irrelevant material." For example, The puppy dog sprinted really fast can be edited to the puppy sprinted. It isn't necessary to add "dog" when you have the word puppy. You don't need to say "really fast" when the word sprinted already means to run fast.
