Gírias translates to "slang" or "colloquialisms". It's an interesting word because it refers to informal language, which is often a challenge for language learners.
In the song, the lyric "O som que eu ouço são as gírias do seu vocabulário" (The sound I hear are the slang words of your vocabulary) suggests an intimate connection, where the speaker is so close to the person they admire that even their unique way of speaking, including their slang, is music to their ears. This highlights a deeper level of familiarity and affection.
ANAVITÓRIA build this one out of small, specific details instead of big declarations, which is exactly the point: the singer keeps calling everything strange, then lists reasons that add up to falling for someone anyway. The comparisons reach for history: Columbus finding land ("Colombo procurou as Índias, mas a Terra avistou em você" [Columbus looked for the Indies, but sighted Earth in you]), and a man walking on the moon ("Se o homem já pisou na Lua, como ainda não tenho seu endereço" [If man has already stepped on the Moon, how do I still not have your address?]). Two enormous, unrelated facts, used to argue that not having this person's address is the actual mystery.
Everything else stays close to the ground. A pair of blue Converse sneakers ("Estranho é gostar tanto do seu All Star azul" [It's strange to like your blue All Star so much]), a specific neighborhood, a specific elevator button: "E entro no elevador, aperto o 12, que é o seu andar" [And I enter the elevator, press 12, which is your floor]. That line is plain on purpose. It reads like a routine, visited often enough that "O tom que eu canto as minhas músicas na tua voz parece exato" [The key I sing my songs in seems exact in your voice] lands less like a compliment and more like something the singer has actually noticed.