Mezcal is a distilled alcoholic beverage made from agave, similar to tequila. It's known for its smoky flavor and often contains a 'worm' (actually a moth larva) at the bottom of the bottle.
In the song, Lazza sings, "come un verme in fondo al mezcal" (like a worm at the bottom of the mezcal). This vivid and somewhat unusual simile evokes a feeling of being trapped, insignificant, and perhaps even consumed, making it a memorable and intriguing word choice.
Lazza wrote a breakup song about refusing to pick up the phone. The messages keep arriving and he counts them in the title: "È inutile che mi angosci, mi mandi cento messaggi" (It's useless to distress me, sending me a hundred messages), and then straight after, "A cui non risponderò, non ne sono più capace" (Which I won't answer, I just can't do it anymore). That second half is the honest part. He is not being cold on purpose. He has run out of whatever it takes to reply.
The rest of the song is him pricing the damage. The money arrived and fixed none of it: "Anche se ho dieci orologi, non recupererò gli anni" (Even though I have ten watches, I won't get back the years). His flat since he threw her out is "Grande tipo il doppio, ma senza la luce" (It feels twice as big, but without the light). He casts himself as the one who loses the fight, which for a rapper is a strange thing to volunteer: "Penso a Davide e Golia, io sarò Golia, tu mi ucciderai" (I think of David and Goliath, I'll be Goliath, you'll kill me). Then the line the whole thing turns on: "Che abbiamo fatto la guerra, ma non sapevamo come fare pace" (That we waged war, but didn't know how to make peace).