Gaviotas translates to "seagulls". It's an interesting word choice because it's not a common animal to feature prominently in song lyrics, especially in a song about life, death, and material possessions.
In the song, the narrator compares himself to seagulls, stating, "Y soy como las gaviotas que vuelan de puerto en puerto" (And I am like the seagulls that fly from port to port). This metaphor beautifully conveys his free-spirited, unattached nature, wandering the world without a fixed home or owner, much like a seagull moving between different ports.
"Un Puño De Tierra" is a classic Norteño ranchera about facing death without regret. The singer describes a free, wandering life: no fixed home, no master, no shame in living by his own rules.
The chorus is the heart of the song: when he dies, he won't take riches or possessions with him, only a handful of earth ("un puño de tierra"). It's a reminder that life is short and that what matters is how you live it, not what you own.