Arda comes from the verb arder, meaning "to burn". While that's its literal meaning, it's used here in a very popular and sassy slang expression.
In the song, the line "Que no te arda estar sin mí" is a defiant taunt that means "Don't let it burn you to be without me." It's the perfect way to say "Don't be salty" or "Don't get bitter" in Spanish, capturing the song's fiery attitude.
This song is the ultimate anthem for when your ex just won't get the hint. Grupo Firme doesn't waste any time with subtlety here. The song opens by asking, "¿Qué parte no entiendes / Cuando te digo que no? / ¿La N o la O?" (What part don't you understand when I say no? The N or the O?). It's a hilarious and brutally direct way of saying that things are over.
The singer makes it clear they have moved on and are living their best life, saying, "Ando tan feliz sin ti" (I'm so happy without you). They've blocked their ex everywhere, but the ex still thinks they have a chance. The song is a command, repeated over and over: "¡Ya, supérame!" (Get over me already!). The singer even accuses their ex of being a sore loser and a liar, telling them, "Tienes que saber perder / Igualito que sabes mentir" (You have to know how to lose / Just like you know how to lie). It's a powerful, confident, and slightly savage breakup song.