Tatúan comes from the verb tatuar, which means "to tattoo". It's a visually powerful word that you won't find in every song.
In the lyrics, Kali Uchis sings the poetic line, "Hay cosas que se tatúan sin tinta" (There are things that are tattooed without ink). She uses this as a beautiful metaphor for powerful memories that leave a permanent, indelible mark on your soul, much like a tattoo, but without any physical ink.
This song is the ultimate post-breakup anthem for when you know you made the right choice. Kali Uchis is completely over her ex and feeling better than ever. She makes it clear that leaving was the best decision, singing, "Fue mejor volar para no caerme" (It was better to fly so I wouldn't fall). She found herself after the relationship ended: "Si cuando te perdí, me encontré" (If when I lost you, I found myself). She knows her ex misses her and is even a little smug about it, with the killer line, "Tú estás con otra, haciendo las cosas / Que en mi cama te enseñé" (You're with someone else, doing the things / that I taught you in my bed).
SZA's verse adds another layer, looking back at a toxic dynamic where it was hard to leave despite the bad treatment. She admits, "Duro dejarte ir cuando lo haces así" (Hard to let you go when you do it like that), but also realizes the truth: "Tú nunca fuiste mío" (You were never mine). Both artists agree that the impact they made is permanent. Kali leaves her ex with a final, confident thought: "Hay cosas que se tatúan sin tinta" (There are things that are tattooed without ink). The memory of her isn't going anywhere.