what does the meteorite have 2 do with ruby, sapphire, & e,arald? thanx?

Answer 1

The metorite powers team Magma's machine. Go to the machine and press "A". You pick up the metorite and then Fly to Fallarbor Town and go to the house left of the pokemart. Talk to the scientist inside the house and he'll give you Tm27-Return for the metorite.
P.S.- In the pokemant in Fallarbor, talk to the lady looking at the shelf on the top, talk to her, and she'll teach your Pokemon metronome. :)

Answer 2

It powers the machine that team magma/aqua use to try to make the whole world earth/water