The official term for Kernels are that they are a softer more edible part of a nut, seed or fruit stone that are contained within its shell.
However they are most popularly what are used to make popcorn from. They have a hard moisture sealed hull which are hard to bite through and a dense starchy interior. When they are heated, pressure builds within the kernel and a mall explosion or pop is the end result. They are often seen at the bottom of a popcorn bag.
So can gerbils eat kernels?
No they can’t there is too much of a risk that they might choke.
They are a food that is best avoided.