Partysea is a fun and modern Spanglish verb meaning "to party". It's a fantastic example of how languages blend, created by taking the English noun "party" and turning it into a Spanish verb using the common -ear ending.
In the song, the line "Y partysea de viernes a jueve'" means "And she parties from Friday to Thursday". This playful lyric emphasizes a carefree, party-centric lifestyle and is a perfect example of the creative slang you'll find in modern reggaeton.
This song is all about a secret, fiery relationship. Jhayco sings about a woman who is successful and independent on her own, but has a wild side she only shows him. In public, she acts like a total stranger: "Se hace la que no me conoce" (She pretends she doesn't know me). It's a game they both play, keeping their connection completely under wraps.
But behind closed doors, it's a completely different story. She lets loose and their time together is intense, described as a "vicio como a las cinco doce" (an addiction like a 512 [a type of Percocet pill]). She even has her single friends acting as lookouts so she can continue her secret life without anyone finding out. He describes her as a "Barbie pero no busca un Ken" (a Barbie but she's not looking for a Ken), meaning she isn't looking for a perfect, public relationship; she just wants to have fun on her own terms.