The ability affects all players, not just you.

If a land is tapped for mana but doesn't produce any (for example, if you tap Gaea's Cradle for mana while you control no creatures), the delayed triggered ability won't trigger.

The effect doesn't wear off until just before your next untap step (even if an effect will cause that untap step to be skipped).

If a land produces more than one type of mana at a single time (as Boros Garrison does, for example), the land's controller chooses which one of those types of mana is produced by the delayed triggered ability.

The types of mana are white, blue, black, red, green, and colorless.