Causal conjunctions belong to the subordinate conjunctions. They indicate the cause or reason of what is being stated in the first of the two sentences. A few examples are: porque, puesto que, para que, ya que, etc.

Let's look at some example sentences.

Laura está enojada contigo porque no bailaste con ella.
Laura is mad at you because you didn't dance with her.

Yo lavé la bolsa de dormir puesto que estaba sucia.
I washed the sleeping bag since it was dirty.

No cambié la llanta porque no pude encontrar el gato.
I didn't change the tire because I couldn't find the jack.

Tuvimos que acortar las vacaciones debido a la tormenta.
You should do it because it's the law.

Ya que vas al mostrador, tráete algunas servilletas de papel.
Since you're going to the counter, bring some paper napkins.

La comida huele bien pues mamá la cocinó.
The food smells good because mom cooked it.