Colmare means "to fill" or "to bridge" in Italian, and while it can describe filling something physical, it's most often used for emotional emptiness, like filling a void that nothing else seems able to touch. It carries a slightly more poetic weight than a plain word like "riempire."
In the song, Coez sings "Tu che mi sai colmare un vuoto come il mare" ("You who know how to fill a void like the sea for me"), comparing that emotional fullness to something as vast as the ocean, which shows just how deep the void being filled really is.
Coez's "Margherita" paints a picture of a complicated relationship, filled with both deep connection and painful distance. The singer reflects on a person who could fill a void inside him "like the sea," a powerful and overwhelming feeling. He felt he had "everything" when he had them, even when his own pockets were empty.
However, this same sea that fills the void also becomes a barrier. It's a force "between the head and the heart" that keeps them apart, never bringing one to the other. The song is full of conflicting emotions: the image of a lover waiting in a car with the engine running, claiming to be fine alone while shedding a tear, captures this perfectly. The lyrics explore themes of regret over past mistakes, the pressures of being in the "spotlights," and the wish that the other person never gets hurt, because falling is a normal part of life.