When a creature explores (via the explore keyword, CR 702.148), one of the possible outcomes is that you may play a land card revealed from the top of your library. Playing a land in this way is still playing a land in the normal sense — it is not a special exception.
CR 305.2 states that a player may play one land per turn during their main phase, and that this counts as their land play for the turn. Any land played through explore's effect uses that same land-play action and consumes your one land drop for the turn (unless you have additional land plays available from other effects).
It is important to note that explore itself does not grant an additional land drop. It simply presents you with the opportunity to play the revealed land using whatever land plays you have remaining. If you have already played a land this turn, you cannot play the land revealed by explore.
Example: It's your main phase and you haven't played a land yet. Merfolk Branchwalker's explore reveals a Forest. You choose to play that Forest — it enters the battlefield, but you have now used your one land drop for the turn and cannot play another land from your hand.
If an effect like Azusa, Lost but Seeking grants you extra land drops, those would still be available after an explore land play, since explore uses one of your land drops, not a special separate action.
Unofficial fan resource — not affiliated with or endorsed by Wizards of the Coast. Answers are AI-generated estimates grounded in the Comprehensive Rules and are not a substitute for an official judge. Verify anything match-critical.