Calefacción literally translates to "heating" or "heater". It's an interesting word choice for a reggaeton song, as it's not typically associated with the genre's themes.
In this song, Danny Ocean uses "calefacción" metaphorically to describe the intense heat and passion he feels for a woman. He compares her presence to the warmth of a heater, especially in the context of living in Europe during summer, creating a vivid image of a scorching, irresistible desire.
Danny Ocean builds a whole flirtation out of one very specific complaint: European summers. "Tú te sientes como calefacción, baby" (you feel like central heating, baby), he sings, and then he explains himself. "Como cuando vives en Europa, baby" (like when you live in Europe, baby), "En verano, baby" (in summer, baby). Anyone who has spent August in a flat built for winter knows the exact heat he means. The compliment is that she is unbearable in the same way.
The song stays in that register for its two and a half minutes, sliding between Spanish and English with the radiator joke running underneath. "Tú no necesitas algoritmo, baby" (you don't need an algorithm, baby) is his way of saying she has nothing to prove to anyone's feed, while "Que se note el frío en tu franela, baby" (so the cold shows through your t-shirt, baby) is considerably less subtle. He opens by spelling out where he is from, "V-N-Z, C-C-S" for Venezuela and Caracas, then switches to English to ask "Can I be your papi flame? Your summer rain?", which is either charming or a bit much depending on your mood. By the end he is just repeating the title until it stops sounding like a utility bill.