ELI5 version: You know how things glow red when heated up? That takes energy, or, more precisely, that converts heat energy to light. And you know how the color changes the hotter it is? Even before its starts to glow red it actually still glows, pretty much everything does, we just dont see it because it falls outside of visible spectrum, but thermal cameras can and that’s how they work. So, for space question, just take a big plate, and unlike solar panels, point it perpendicular to the sunlight. Run some coolant through it and you’ve got a space chiller. If you look at i.e. ISS photos you’ll see big solar arays at the sides and smaller jagged square panels protruding off the middle and some off the sides, those are exactly it, the so-called “heat rejection units”. Actually while double checking myself I was surprised to learn that they do not run a thermal pump between radiators and everything else, I always thought they did as hotter objects dissipate more energy, but apparently shipping more radiators to orbit was a better tradeoff than constantly wasting energy pumping the heat away.