Not at all with 全然〜ない
Grammar: Degree » 全然〜ない
The adverb 全然 followed by a negative verb or adjective gives the meaning “not at all”, such as “do not understand at all” or “am not happy at all”.
Examples
Not understanding at all with 全然〜ない

During an underwater-breath-holding contest, Cocoa begins a game of charades. Syaro doesn’t understand at all what the gestures are supposed to mean.
- シャロ:
- 「全然わからない」