Yup, you got it

This sometimes feels counterintuitive because in traditional media more blue means more pigment, typically means a darker colour. If I was mixing paint I might be inclined to say that the navy blue is bluer than, say, a sky blue. And if you've ever tried to mix all the colours in your palette, you've probably wound up with a really muddy brown or even black

But digital colours are mixed with light, so as you add more colour the result is brighter. Which is why if you add all the light (#FFFFFF) you end up with white and if you use no colour at all (#000000) you end up with black