Definitions of holler:

• noun:   a small valley between mountains
• noun:   a very loud utterance (like the sound of an animal)
• verb:   shout out

  Example: "He hollered out to surrender our weapons"

• verb:   complain

  Example: "What was he hollering about?"

• verb:   utter a sudden loud cry
• name:  A surname (rare: 1 in 50000 families; popularity rank in the U.S.: #5445)