In Deus Ex: Human Revolution for the PC, PS3, and Xbox 360, the augment actions you can take usually require energy. Energy comes from your battery cells though, which can limit how many actions you can take within a certain amount of time.
The first energy cell will refill automatically within a certain amount of time, depending on the augments you have, but the rest will not automatically fill.
In order to fill the rest of the batteries in the bar, you need to eat some sort of Cyberboost Proenergy item.
Cyberboost Proenergy comes in three forms: bars, packs, and jars. Bars refill one energy cell, packs refill two energy cells, and jars refill three energy cells.
These Cyberboost Proenergy bars are scattered throughout the game, and are also sold by some vendors in the game, so stock up on them if you can because you will need them from time to time.
