Equivocación translates to "mistake" or "error." While it might seem straightforward, its use here is particularly poignant and educational.
In the song, the lyrics advise the heart, "Para evitar la equivocación, corazón ya sabes qué hacer" (To avoid the mistake, heart, you already know what to do). It's a powerful warning against repeating past romantic errors, making it a memorable and relatable word for anyone who has experienced heartbreak.
The whole song is addressed to the singer's own heart, treated as a separate person who keeps making the same mistake. He opens by scolding it gently — "Corazón, no seas así, fíjate de quien te enamoras" (Heart, don't be like that, look who you fall in love with) — and points out that the last love, the one that soothed the old wounds, ended up leaving another one behind.
The chorus sets a condition rather than a ban: "Si te vuelves a enamorar... es mejor que sea la ultima vez" (If you fall in love again... it had better be the last time). The reason he gives is that the pain is shared — "tus penas son las mías también" (your sorrows are mine too) — so the heart's next mistake would be his to carry as well. The second half turns practical: temptations are everywhere, draw on what experience has already taught you, and "ten cuidado de no caer" (be careful not to fall).