What is meant by an excited atom?

All that is meant by an 'excited' atom is that one or more of the atoms electrons in it's shells, are then excited into shells that are in higher energy states that they were in before.

Furthermore, electrons can be excited by high speed electrons that collide with the bound electron in the atom shel. Or the electron absorbs a photon of energy that excatly equals the energy differece between the two energy states.