Load averages are the three numbers shown with the uptime and top commands – they look like this
The three numbers represent averages over progressively longer periods of time (one, five, and fifteen minute averages) and that lower numbers are better – higher numbers represent a problem or an overloaded machine
The problem with a load of 1.00 is that you have no headroom – in practice many sysadmins will draw a line at 0.70