Colo is a beautiful and versatile Portuguese word that literally means "lap" (as in, a person's lap). However, it's most commonly used to express the idea of comfort, a hug, or a cuddle, especially from someone you trust and feel safe with.
In the song, the singer is heartbroken and vulnerable, having lost a great love. When he sings "Quero colo," he's not just asking for a lap to sit on; he's expressing a deep need for emotional comfort, warmth, and reassurance from another person. It's a very tender and relatable expression of needing solace.