I guess the title says it all.

Google'd, hope this helps.
http://www.cooltechzone.com/index.php?option=content&task=view&id=377&Itemid=0

Sorry, didnt help much... I need someone like deathhawk or felagund to explain it for me..

Latencies are just basically how many cycles it takes the memory to perform a certain operation.

I was looking for a more complete answer, I need a pretty good idea of what it is, what its for and how it works.

Basically, the reaction time for the RAM.

If you want to understand it, go read articles about it. All you need to know is lower equals (slightly) faster, but go too low and you'll lose stability. Also, increasing the voltage to your RAM can help increase stability for "tighter" (lower) timings, but every stick of RAM has its limits. Generally, you don't really need to be concerned with memory timings - I'd rather have 4 Gb of decent RAM over 2 Gb of great RAM any day of the week. So keep this rule of thumb for buying RAM - don't pay more (than like $10 or $20 more if you want slightly better Ram) for better memory timings, if the two pieces of RAM you're comparing are at the same speed. One other thing you should understand is that faster RAM speeds generally have slower/higher timings, and DDR2 has slower/higher timings than DDR, etc. etc. Therefore, DDR2 1066 has slower timings than DDR2 800, and so on and so forth.