what the hell is that number?!

[Pgentry]

Okay so I've been reading up on gears and gear ratios but I still need a little help, I understand the higher the gear ratio is, the quicker the acceleration is by spinning the driveshaft that numbers amount, in comparison to turning the wheel once...my question is why are people asking if like 3.83 is a good gear ratio for performance (using those numbers as complete example..I have no idea if that's good or not) how do u know what's good performance and I thought each gear has its own gear ratio- why aren't people asking for 5 numbers for 5 gears...? Is it the final gear that they're talking about? And what is that? Hahaha and lastly what gears are good for our curvy triangled motored tranny?..