The noun has one meaning:
Meaning #1:
a very loud utterance (like the sound of an animal)
Synonyms: bellow, bellowing, holla, holler, hollering, holloa, roar, roaring, yowl
The verb hollo has 3 meanings:
Meaning #1:
encourage somebody by crying hollo
Meaning #2:
cry hollo
Meaning #3:
utter a sudden loud cry
Synonyms: shout, shout out, cry, call, yell, scream, holler, squall
