It can refer to:
* A sweet treat or dessert: "Quiero comer el dulce después de la cena." (I want to eat the sweet after dinner.)
* Something sweet in taste: "El dulce de la fruta me gusta mucho." (I really like the sweetness of the fruit.)
* Something pleasant or enjoyable: "El dulce de la vida." (The sweetness of life.)
Keep in mind that the specific meaning of "el dulce" will depend on the context of the sentence.