Explore

• WWizards of the Coast2017-03-14
  Official Ruling
  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.
• WWizards of the Coast2017-03-14
  Official Ruling
  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.
• WWizards of the Coast2017-03-14
  Official Ruling
  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.

Rulings via Scryfall