How can the sun have both a brightness of -26.73 and 4.83? explain what these numbers mean.

The Sun has an "absolute magnitude" of 4.83 and an "apparent" magnitude of -26.8. (Which is the difference between the numbers). Scientists use what is know as "Absolute" Magnitude to help them understand and compute how bright a star really is. The "absolute" magnitude of an object, such as a star, equals how bright that object would look if it were 10 parsecs, or 32.6 light years away from the Earth.

From negative to negative