Dulcito e' coco literally means "little coconut sweet" and refers to a popular Caribbean dessert. This phrase is a beautiful example of colloquial Spanish.
Dulcito is the diminutive of dulce (sweet), adding a sense of affection, while e' is a common contraction for de (of). In the song, Vicente Garcia uses this sweet treat as a metaphor to describe his lover, comparing her gaze and lips to the delicious, comforting flavor of coconut candy.
This song is a beautiful declaration of love and need. Vicente Garcia starts on a pretty dark note, saying he's on a road to misery: "Fui a subir la carretera / Que me lleva a la miserĂa" [I went up the road / that leads me to misery]. He feels like he's being beaten down and asks for a fight rather than just being thrown on the ground.
But then, the whole mood changes. He reveals what he's missing: the sweet, unique quality of his love, which he compares to a "Dulcito e' coco" [Sweet little coconut]. He says he misses the "saborsito a coco que sé que hay en tu mirar" [little coconut flavor that I know is in your gaze]. He compares her to a honeycomb and says he needs her more than anything else. He begs her to change his path from that road to misery to the one that leads to her house, asking her to take away his grief. It's a simple, direct plea from someone who sees his partner as his only source of sweetness and relief.