Che ca**o vuol dire

It translates roughly to what the fuck does that mean or what the hell does that mean in English. Cazzo is a vulgar Italian swear word, so the phrase is much stronger and more frustrated than a polite what does that mean.

The clip is about one second long, just long enough for the full shouted phrase. That very short length is why editors use it as a sudden punch in reaction videos, cutting in and out before the next scene starts playing.

Use it when a character, friend or caption says something confusing, illogical or badly explained. The angry Italian delivery signals instant disbelief and frustration, so it works best as a reaction to nonsense rather than as background audio or a calm explanation.