Amanecer is a beautiful Spanish word for "sunrise" or "dawn." It can also be used as a verb meaning "to dawn" or even colloquially "to wake up," making it a versatile and poetic word.
In the song, Camilo sings about experiencing "un amanecer bonito" (a beautiful sunrise) for the first time with his love. This word perfectly captures the song's theme of new beginnings and the magical feeling of seeing the world in a new light with someone special.