Imagine a sine wave to represent a photon. The sine wave is 2d. Now Imagine being able to rotate the sine wave around the neutral axis. To us, the light looks the same. To them, the light looks different.

Normal light is a bunch of these waves at different frequencies and adjusted forwards/backwards in a random fashion.

If you could adjust them such that they're all aligned, which we can do with certain materials that block light paths that come in at the "wrong" angle, but turn the intensity back up, you and I can't tell the difference between the before/after. They can.

And I guess we might not have the vocabulary to describe what they see, but there are some women who are tetrachromats who basically describe colors and patterns only fellow women tetrachromats can see.