What does it mean to use redundant adverbs?

Avoid using two or more adverbs at once to show a greater degree of an idea or concept.
Incorrect: The young lady walked down the runway extremely very poorly.
Correct: The young lady walked down the runway extremely poorly.
Correct: The young lady walked down the runway very poorly.

Also, redundant words or phrases, such as repeat again or return back, are poor examples of the proper use of grammar.