Farreando is a cool slang term from Colombia and other parts of Latin America that means 'partying'. It comes from the noun farra, which means 'a party' or 'a bash', and is more casual and lively than the standard verb festejar.
In the song, Feid sings, "Me la he pasado farreando" (I've been partying), to describe how he's coping with heartbreak. Learning this word is a great way to sound more like a native speaker and understand the authentic slang used in modern reggaetón.
Feid is going through it in this one! He starts off trying to sound tough, like he's totally over a breakup. He tells his ex, "Te juro que hoy te dejo en paz" (I swear I'll leave you in peace today), but then immediately follows it up with "Nadie te va a amar como yo, mami, sobre la faz" (No one will love you like me, mommy, on the face of the earth). It's that classic mix of heartbreak and ego, where he's trying to convince himself he's fine while also reminding her what she lost. He feels like he was just a temporary stop for her, saying, "Pa' ti yo siempre fui un motel" (To you I was always a motel), which is such a blunt way to put it.
But then he admits how much it actually hurts, saying he pretended it didn't hurt, "y duele el doble / O el triple cuando el cora' se rompe" (and it hurts double / Or triple when the heart breaks). He's confused because he's hearing rumors that she misses him, even though she's the one who ended things. He's trying to move on by partying, or "farreando" as he says, but he's still stuck on her. The whole song feels like that messy, confusing stage of a breakup where you're trying to act cool but you're really just sad and a little angry.