Jangueíto' is a Puerto Rican slang term, a diminutive of "jangueo," which comes from the English phrase "hanging out." It refers to going out to party or hang out, often in a casual and frequent way.
In "Mi Vecinita," the lyrics state, "Mi vecinita le gu'ta los jangueíto'" (My little neighbor likes to party/hang out). This word is interesting because it's a Spanglish term unique to Caribbean Spanish, particularly Puerto Rico, and perfectly captures the song's theme of a young woman who enjoys going out and having a good time.
"Mi Vecinita" ("My Little Neighbor") is a fun, upbeat reggaeton track by the Puerto Rican duo Plan B (Chencho y Maldy), from their album of the same name.
The song describes a neighbor girl who has fully embraced the reggaeton party scene. She used to stay quiet at home, but now she goes out with her beer, follows the latest music, and dances all night without any fear of what people think. The chorus calls her "adicta" (addicted) to the beat, the club, and the whole lifestyle.
It's a lighthearted celebration of letting loose and dancing freely, name-checking the artists and the label (Pina Records) along the way, in classic 2000s reggaeton style.