At level one you get 3 level 0 spell slots (these are called orisons, you get to use them as much as want), and 2 level 1 spell slots due to your wisdom modifier. Plus an additional level 1 slot for your domain spell.
So you pick 2 domains. Each domain allows you to cast specific spells. This is where clerics can get interesting because you can gain access to spells not on the cleric spell list