Translation:E paʻa ka waha.
waha = n. a mouth; an opening generally.
The mouth of a person; E olelo he waha no he waha, To speak mouth to mouth.
paʻa = 1. nvs. A common and broadly used loaʻa-type word; many meanings depend on qualifying words. ...
13 11. To hold back; to be detained from doing a thing; aole i hiki, ua hoopaa ia ia Kamehameha, he could not (return), he was detained by Kamehameha.
kēnā = that (near the person addressed)
E paʻa kēnā waha. = (Hold back that mouth.) Be quiet.
Why is "E hāmau" not the better answer? The choice I was given was "E pa'a kēnā waha", not "E pa'a ka waha." It might be a typo error.