'Culturally linked start locations' means that civs in the same cultural group (American, Mesopotamian, European, Far East, Mediterranean/Græcorroman) start as neighbours instead of all being scattered at random.
'Respawn AI players' means that if you kill the AIs early on they'll respawn. You can conquer Tenochtitlan several times!
'Preserve Random Seed' IIRC, means that you can't replay turns and get different combat results. They'll be played out no matter what.
'Accelerated production' means exactly that, everything is produced faster.
The last two are on the civilopædia for sure.