What is black body radiation?
A black body is an idealized physical body that absorbs all incident electromagnetic radiation. The thermal radiation from a black body is energy converted electrodynamically from the body's pool of internal thermal energy at any temperature greater than absolute zero. It is called blackbody radiation and has a frequency distribution with a characteristic frequency of maximum radiative power that shifts to higher frequencies with increasing temperature.
The answer to Planck’s law of black body radiation calls for an understanding of concepts, the scope of which go much beyond the ambit of the syllabus in your current grade.