I would take pen and paper and draw a dot. This will be my nucleus of an atom. The I would say thet I was in that nucleus, measuring the position of the 1s electron around me. The 1s eletcron is my closest friend under the electrons. Then I would draw around that nucleus a lot of small dots with the correct radial distribution explaining that every dot is one position measurement of that same 1s electron. Then I would say that there is a sphere around the nucleus where the nucleus was mostly seen. The radius of this sphere was measures by Niels Bohr and is therefore called the Bohr radius