To perform any action, Tavern Girls must be selected from the control menu on the right side of the screen. The actions available to them depend on whether or not they are currently inside the pub.
When inside of the pub, Tavern Girls can serve guests. If the Pub is upgraded to at least a Shebeen, they can also perform exotic dances.
When outside of the pub, Tavern Girls can provide 'salacious services'. If the Pub is upgraded to at least a Shebeen, they can also be sent to distract guards. Note that Tavern Girls can be sent inside the pub to perform these tasks, but the option to do so is not available until they are outside of the pub.