Rancherita is a charming, diminutive form of ranchera, meaning 'ranch woman' or 'woman from the countryside'. It's a term of endearment deeply tied to the culture of traditional Mexican ranchero music.
In the song, Christian Nodal uses it as a flirtatious compliment, calling his interest a '¡Ay, qué chula rancherita!' (Oh, what a cute little ranch girl!). This single word perfectly captures the playful, romantic, and cultural vibe of the duet.
This song is a super fun back-and-forth between a guy who's trying his best to win a girl over and a girl who is not making it easy for him. He sees her and is instantly smitten, calling her a “¡Ay, qué chula rancherita!” [Oh, what a pretty little ranch girl!]. But she immediately shuts him down, telling him that pretty words aren't enough to win her over and that she's not like the other girls he's used to.
He then tries some classic romantic moves. He asks, “¿Y si te llevo rosas?” [And if I bring you roses?], but she just replies that they'll wilt. So he suggests a serenade, “¿Y si te llevo serenata?”, and she bluntly tells him her dad will just chase him away. He's desperate, promising, “Este vato se hace a tu manera” [This guy will do it your way], but she points out a pretty big problem: her friends and family don't like him at all. It’s a playful duet about a persistent suitor with a bad reputation and a smart girl who wants more than just sweet talk.