Se vale to' is a catchy colloquial version of se vale todo, meaning “anything goes” or “everything is allowed.” The final -do in todo is dropped in the song's pronunciation, a common feature of Caribbean and urban Spanish. As the repeated hook, the phrase captures the song's carefree, rule-free mood and is a memorable example of informal Spanish.
Se Vale To is Kevin Roldan's anything-goes party anthem, and the title says it all: "Hoy se vale to'" (today everything is allowed). To' is just todo (everything) chopped short, the way it's said in Colombian and Caribbean Spanish. You'll see that dropped ending all over the song: "nos vemo'", "nos olvidamo'", "nos matamo'" are vemos, olvidamos, matamos with the final s swallowed.
The story is an on-and-off thing between two people: "Cada ve' que nos vemo', del mundo nos olvidamo'" (every time we see each other, we forget the world), then "después nos desconectamo'" (afterwards we disconnect), and "aunque pase el tiempo, volvemo' y hablamo'" (even if time goes by, we come back and talk). "Nos matamo', nos comemo'" (we kill each other, we eat each other) isn't violent at all; it's slang for a very heated make-out.
Then it gets explicit fast. There's a hotel suite, a phone switched off ("¿Ya le apagaste el cel?", did you turn off your phone already?, cel being short for celular), lingerie, and some pretty graphic lines near the end. He also name-drops party drugs: tusi is the pink powder drug popular in Colombian nightlife, and "me encantan las pastilla'" (I love pills) is exactly what it sounds like. The sweet moment is "tu boquita sabor a miel" (your little mouth tastes like honey), where boquita is the cute diminutive of boca.