This is the 165th most frequent Ukrainian word.
нічого
"Нічого" means "nothing" or "it's okay" (depending on context).
In this context, 'нічого' is used as a pronoun indicating 'nothing' in a direct negation.
Я нічого не бачу.
I see nothing.
Here, 'нічого' is again used as a pronoun meaning 'nothing,' referring to the impact of an action.
Це нічого не змінює.
This changes nothing.
In this set phrase, 'нічого' is used to imply 'nothing' in a comforting or minimizing context.