P A N

it basically means your neck is a bit warped. it doesn't mean it's permanent necessarily though. chances are it can be fixed, but if you don't know what you are doing it's not something you really want to watch a couple youtube videos on and have at'er. it's generally a combination of adjusting your truss rod (the piece of cylindrical steel running down the length of the neck) and your bridge nut. depending on whether or not your bridge nut is all spring-loaded and screw-fitted, it may be a matter of actually filing it down, which is kind of an art. having your intonation set up properly shouldn't cost you much really. i wouldn't stop at my post though. i'm no expert on the matter by any means.

EDIT: and as far as the definition of intonation, it's basically a matter of resonance. if things are all perfectly aligned and whatnot your instrument will resonate properly and vice verse. buzzing is generally a sign that your neck is slightly bowed backward and when you vibrate the string they slap up and down on a fret at a pretty high rate. hope that helps.

edit 2: pardon my idiocy. i only read the last post and the title.