2017-03-14 : Explore's effect allows you to play an additional land during your main phase. Doing so follows the normal timing rules for playing lands. In particular, you don't get to play a land as Explore resolves; Explore fully resolves first and you draw a card, perhaps a land you'll play later.

2017-03-14 : If you somehow manage to cast Explore when it's not your turn, you'll draw a card when it resolves, but you won't be able to play a land that turn.

2017-03-14 : The effects of multiple Explores in the same turn are cumulative. They're also cumulative with other effects that let you play additional lands, such as the one from Urban Evolution.