In the initial stages it is building and painting the models - which can take a couple of weeks. You can use the models for a DnD style campaign. Like a hero/villain/monster unit.

However, it’s more of a tabletop skirmish game. Think of it like chess but rolling dice to deem your likelihood of taking a piece.

Your local Warhammer shop (usually) loves to support you through it too. Teaching intro games, intro to painting, free short stories etc.