Despegar literally means "to take off," as in an airplane taking flight. It's an exciting and dynamic word that evokes a sense of beginning a journey or reaching new heights.
In this song, the artist uses it in a more metaphorical and suggestive way: "Con Adderall ya vamos a despegar" (With Adderall, we're about to take off). Here, "despegar" implies the start of an intense, perhaps wild, experience, fueled by the effects of the substance, setting the tone for the hedonistic themes of the song.
Blessd spends this whole song on a yacht and never pretends otherwise. It opens on Atardecer en un yacht (sunset on a yacht), En la bahía, lejos de la gente (in the bay, far from everyone), with the air conditioning at sixteen and an Adderall before takeoff. After that it turns into a running inventory of what the money buys: the Gucci bikini, the little purse he fills with bills, Dos esmeraldas en tus ojos y los arete' (two emeralds in your eyes and in the earrings), a flight to Cartagena whenever he feels like calling her. Most of the rest is far too explicit to quote, and Blessd is plainly enjoying that.
What stops it being only a list is the line he keeps coming back to, Mi amor, soy tu fan (my love, I am your fan), which closes every chorus. The third verse pushes the same contradiction harder: Yo le digo que ella es mi perra (I tell her that she is my bitch) sits one line above Pero que también es mi vida (but that she is also my life). He describes the arrangement honestly exactly once, in Aunque seamo' casi novios, casi flete' (even though we are almost a couple, almost just a hookup), and then goes straight back to the yacht. There is a lot of Medellín street Spanish to pick up along the way, from pa' standing in for para to chimbita for a good-looking woman and fresquitos doing a lot of work in the opening verse.