Most roleplaying games could be split up in at least three parts: Social encounters and roleplaying, Combat and exploration.
This does not mean there are no additional pillars for any game. Some tabletop game lends itself to other pillar or not have any of the aforementioned pillar. Another pillar could be for example downtime & crafting.
Reference
Let’s Design an Adventure: Encounters and the Three Pillars
Highlights or timestamps
Let’s Design an Adventure: Encounters and the Three Pillars Highlights
- the game’s designers talked frequently about the “three pillars” of D&D: combat, exploration, and roleplaying/social interaction
— ^f651d9 from Let’s Design an Adventure: Encounters and the Three Pillars Highlights