According to the illustrations, Y is pointing at electrons.
Atoms are generally known to be composed of neutrons that have no charge, electrons that are negatively charged, and protons that are positively charged.
In the atom of every element, the proton and the neutron make up the nucleus while electrons are distributed in the shells surrounding the nucleus.
Thus, looking at the image, the part labeled X would be the nucleus while the part labeled Y would be some, not all, of the electrons of the atom.
More on the atom can be found here: https://brainly.com/question/1566330
