(feminine) force; strength
(feminine) ability to exert influence on others; authority; power
(feminine) force
(colloquial,feminine) electricity
(feminine) series of means used to force someone to do something; violence
(feminine) strong capacity for action of something; intensity
(feminine) muscular energy; robustness
(feminine) spiritual, mental or psychological energy; courage
(feminine) cause; reason
(feminine) set of troops, ships, planes or elements of two or more of these combat assets, intended to carry out a policing or combat mission
(feminine,informal) hernia

Used to wish someone the strength to persevere through whatever hardship they are experiencing, or to encourage someone to do something.