To play a card means to play that card as a land or to cast that card as a spell, whichever is appropriate. The main differences are: Casting a spell uses the stack and you must have priority to cast it
However, we can see from the use of two set icons that there are likely still Commander-focused cards coming, despite the lack of a precon, and this could be one of them.
Unfortunately, like the two cards before, Silvergill Adept is pretty worthless outside of a dedicated Merfolk deck, which is why I have these three listed together here and not at the top of the list
If you kill the Fable, they keep the treasure-making Goblin
Domain cards aren't universally great, but the best ones have stood out in various formats
Ancient Grudge is mostly for Affinity, but you can also use it against Grafdiggers Cage or Relic of Progenitus if you need to