In a blog post, Google tells us to consider how a current computer might find the lowest point in a series of hills and valleys. A classical algorithm would start at a random point and see if it can walk lower, repeating the process until it can no longer descend. Unless it got lucky with its starting point, there’s a good chance the algorithm gets stuck in a local minimum, not the absolute minimum—it’s a solution, but not the optimal solution.

A quantum computer, meanwhile, would be able to consider multiple valleys simultaneously. It’s like “tunneling” through adjacent hills to see whether the valley next door is lower than the valley you’re in currently, thus raising the likelihood you find the lowest point.

It's over my head but it seems quite important.

Status of my credulity:  stretched.  (I doubt it's over your head)

Myself, I'm on my third read.