You bellow encouragement to your allies and bolster them for the next assault.

As an Action you can choose up to six friendly creatures that can hear, see, and understand you, and are within 60ft. Each of those creatures gain temporary hit points equal to your fighter level + CHA modifier. 

In addition, The next attack each of these creatures makes adds your proficiency modifier to their attack and damage roll.  

A creature can't benefit from this feat again until it has finished a short or long rest.