Melao is a colloquial form of melado, meaning a thick, sweet syrup made from sugarcane, similar to molasses. In the song, it refers to the syrup boiling in a large pan during Cali's festival preparations, giving the celebration a distinctly Colombian flavor.
"Oiga, Mire, Vea" is basically a three-and-a-half-minute invitation to Cali, Colombia's salsa capital, during its big December fair, the Feria de Cali. The title is the way people in Cali grab your attention: "Oiga, mire, vea" [Listen, look, see]. It opens by telling you how you will know you have arrived: "Si huele a caña, tabaco y brea, usted está en Cali" [If it smells of sugarcane, tobacco and tar, you're in Cali]. Then comes the bragging, and it is cheerfully over the top: "Aquí no hay fea para que vea" [There's no ugly woman here, you'll see].
The verses read like a party itinerary. Sugarcane syrup bubbles all night ("el melao hierve en la paila hasta amanecer" [the cane syrup boils in the pan until dawn]), there are bullfights by day and dancing at night, and the party "empezó en la sexta" [started on Sixth Avenue] before heading to Juanchito, the riverside district famous for its salsa clubs, "a rematar" [to finish it off]. Barrio Obrero is a working-class neighbourhood with deep salsa roots, so going there turns you into a "rumbero" [party animal]. My favourite part is the practical advice: if you get overheated, have a "raspao" [shaved ice with syrup], take it slowly if you're already "prendido" [tipsy, literally "lit up"], don't drive or you'll land in "un lío" [a mess], and once you're worn out, go cool off in Pance, the river just outside the city. Learner tip: "goza'" and "pa'" are clipped forms of "gozar" and "para", exactly how people talk on the dance floor. And the ending is pure Cali pride: the women there "tienen sabrosura porque mueven la cintura" [have flavour because they move their waists].