When is an act or omission punishable by section 654 of the California Penal Code punishable by multiple punishments?

Penal Code section 654, subdivision (a) provides, in pertinent part: "An act or omission that is punishable in different ways by different provisions of law shall be punished under the provision that provides for the longest potential term of imprisonment, but in no case shall the act or omission be punished under more than one provision." When multiple offenses are committed during an indivisible course of conduct, section 654 bars multiple punishments. (People v. Harrison (1989) 48 Cal.3d 321, 335.)