Lunar is a wonderful word that literally translates to "beauty mark" or "mole". It's derived from luna, the Spanish word for moon, because of its often round shape.
In this tender song, Bad Bunny sings about the small, specific things he adores about his partner, including "el lunar cerquita de tu boca" (the beauty mark near your mouth). It’s a deeply romantic and intimate detail that shows how love is often found in appreciating the little things that make someone unique.
This song is a huge, warm declaration of love. Bad Bunny starts by saying he's been following his heart for a long time, but this new person has completely changed his world. He feels like he's been reborn, singing, "Y solo mírame / Con esos ojitos lindos / Que con eso yo estoy bien / Hoy he vuelto a nacer" (And just look at me / With those pretty little eyes / With that I'm fine / Today I have been born again). It's a feeling of starting fresh after a long time of being alone; he admits, "Hace tiempo que no agarro a nadie de la mano" (It's been a long time since I've held someone's hand).
He describes falling in love as an unexpected accident, saying "Yo no te busqué / Chocamos en el trayecto" (I wasn't looking for you / We crashed on the path). He's so into this person that he's ready to leave his old life behind without a second thought. He lists all the simple, romantic things he wants to do, like gifting sunflowers and collecting seashells at the beach. He's not interested in perfection, either. He tells his love that making mistakes is beautiful, "Y equivocarse es bonito / Los errores son placeres" (And making mistakes is beautiful / Errors are pleasures). The whole song feels like a spontaneous, joyful rush into a new relationship, leaving everything else in the dust.