Parquear is a common example of 'Spanglish,' a blend of Spanish and English. It's an adaptation of the English verb 'to park' and is widely used in Puerto Rico (where the artists are from) and other parts of Latin America instead of the more traditional Spanish word, estacionar.
In 'Desesperados', the singers use this colloquial term to set a scene of urgent passion, explaining that they were so desperate they had to pull the car over immediately. It's a perfect example of how modern, regional slang makes its way into music.
This song is all about a physical connection that's so intense it can't wait. Rauw Alejandro and Chencho Corleone sing about being completely overwhelmed by desire for someone. They literally have a hotel room booked, but the feeling is too strong to even make it there.
The whole story is in the chorus: "Tengo reservado el hotel / Pero con estas ganas no vamos a llegar" (I have the hotel reserved / But with this desire, we're not going to make it). So what do they do? They become "dos desesperados" (two desperate people) who have to park the car because the "asiento" (back seat) is waiting for them. The song makes it clear this isn't a one-time thing. Their lust, or "bellaquera", takes over whenever they see each other, and they admit, "donde sea nos comemos" (we get it on anywhere). There's even a hint of drama, as one line says, "me buscas aunque sabes que tengo a otra" (you look for me even though you know I have someone else).