The Red Bull slogan is a metaphor implying that the drink stimulates you to feel energized, focused, and empowered—giving you the "wings" to perform or excel.
The reason it is now sometimes spelled with three 'i's (Wiiings) is due to a false advertising lawsuit. To settle the claim that the drink didn't literally or figuratively enhance performance as promised, Red Bull changed the spelling to make the phrase legally indefensible as a literal claim.