It means something like: "for real", "seriously"or "I swear ". Also can be used to mean "right away"

Mercury retrograde is the act of taking a shit whilst mooning one or more human beings. Your day can typically being going well, according to your horoscope, until you are forced into witnessing Mercury retrograde. Performing Mercury retrograde will often speed the astrological cycle forward for the individual performing the Mercury retrograde, bringing about happy and fruitful times to come.

another use of tha term "for sure" (fasho) used mostly in the south like new orleans

Basically it is agreeing with someone or saying ok.

awesome, dope, cool, good lookin, fine ect.

To do something right then and there