With the Cashouts, you can Cash Out of the tournament any time you would like, for the amount that your percentage of chips is worth.
So lets say there are 100 people in a $1 tourney and everyone starts out with 1500 chips... you could legitimately cash out right at the beginning of the tournament for your $1 back, or you could wait and accumulate your chips.
Now after accumulating chips you build your stack to 15000 chips, if you cashed out right now, and everyone was still in the tournament(probably not going to happen, but easier to explain), you would get 10% of the prize pool($10).
Now, is it better to cash out or go for the win? You just need to look at the payout structure, but depending on how much you accumulate chips, it can be a much better idea to cash out.
Hope that helps!