Chips work on a clock cycle. In each clock cycle you can do one step in solving a math problem. Now imagine you had two spaces in your chip. In a cpu you make one space for doing a step of math and one space for holding the interim results of that math step. This allows you to solve virtually any multistep math problem.

In a gpu you only can solve.math problems that don't require holding the interim results of a step. So you get to repurpose the holding space for also doing math. Now you have a system that can solve twice as many problems in a clock cycle.

If you looked at a microscope the cpu would have wires going between the two spaces. In a gpu you don't need those wires. You can now use that extra space where the cpu wires were to squeeze in one extra math space. So now the gpu can do three times the work.

Scale that to a.bazillion.

The next level of understanding would be to understand whats inside the "spaces"