Does section 654, subdivision (a) of the California Criminal Code prohibit multiple punishment under the same law?

As applicable here, section 654, subdivision (a) provides that "[a]n 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." The purpose of this statute is "to insure that a defendant's punishment [is] commensurate with his culpability." (People v. Perez (1979) 23 Cal.3d 545, 552 (Perez).) Where section 654 is applied in order to prohibit multiple punishment, "the trial court must stay execution of sentence on the convictions for which multiple punishment is prohibited." (People v. Reed (2006) 38 Cal.4th 1224, 1227.)