PvE stand for Player versus Environment. Which means any in-game activities that related to killing monster, doing quests and participating in any in-game scripted/unscripted events.
The most common PvE elements in Ymirheim are monster hunting, quests and dungeons. PvE activities can reward the players with experience, items, gear, cards. They are also the most common way to gain in-game currency.
The players can participate in PvE alone or in a group (which usually called a party).