basically, look at the title.
It means on the notes are what they should be at a certain fret, IE on the high E the 12th fret note should be an E, etc.
you do it by making sure each note at the 12th fret sounds the same as its harmonic at the 12th. You fix it by adjusting the saddles.
proper intonation = guitar stays in tune all the way up the fretboard.
It means you don't know the proper way to use the terminology.What exactly does changing the intonation on your guitar mean?
You don't "change" the intonation. You adjust it.
The three posts before mine, describe the results of proper intonation adjustment.