A out is how many cards you have in the deck that will give you the best hand and probaly the win. Example. You have a (a,a), and your opponent has (k,k) and the flop comes 2,k,4 all different suits. You are now losing, and you only has 2 outs in order to win, one or both of the other aces. So lets go back to the chart and see what his odds are. Okay the chart says you have a 8.4% chance of hitting that ace on the turn, and river. Lets say it doesnt come, a 7 hits on the turn, now your still relying on one of the two aces on the river. Back to the chart, there is a 4.3% chance that an ace of the remaining 2 will hit on the river.
Here is another example you can figure out for yourself:
You: A(D) K(D)
Opponent Q(H) Q(S)
The flop: 2(D) Q(D) J(H)
Q:Now, how many outs do have to win?
A: 9, is right because there are still 9 possible diamonds that will come on the turn or the river to make you a flush, and probaly the win.
Q: What is your % to win then?(refer to chart flop to river section, because you have 2 chances the turn and river)
A: 35%
The Turn: 10(S)
You did not hit any your outs but you still have the river.
Q: Now how many outs do you have now?
A; Still 9, because if the queen does come to complete your straight, it will give your opponent the 4 of a kind.
Q: So your % drop to what (refer to chart Turn to river, cause you only have 1 chance, so the % will be lower then flop to river.)
A: right, 19.6%
I hope you see how it works now!