The definition of holla, or hollo, is a slang term meaning holler, which is a shout or call.
(noun)An example of holla is giving someone a call on the phone; give them a holla.
See holla in Webster's New World College Dictionary
interjection, noun, intransitive verb, transitive verb
Origin: < Fr holà < ho, ho + là, there < L illac, there
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