I suppose this is another description of the A5 chord, X02255, low to high. No third means it's neither major or minor and usually then contains only the root and fifth intervals in various numbers. I would play the G5 as 3X0033. The A5 form is movable up and down the fretboard for other "5" chords too. A nice D5 is X00235. There are of course, the other "5" chords commonly known as "power chords" eg, G5 (355xxx), A5 (577xxx), B5 (X244XX), etc.

Clear as Mud, Cat?

Mooh.