1: Exploring wilderness. This is a classic, medieval Western European Dark Ages trope. "We are a tiny village surrounded by uncharted wilderness."
This is supported by the hexcrawl style of play. But 1/
There's another context in which I think of "exploration" and that's "going to the bottom of a dungeon."
D&D from 1974 to about 2008 rewarded exploring dungeons with Cash and Magic Items, both of which were at LEAST useful and often CRITICAL to your PC.