The Highlight ribbon consists of three buttons and two sliders.
The first button highlights the current selection and makes the rest transparent or even completely hidden depending on the status of the slider on the right.

The second button only has an effect if the first button is active. It is especially useful if a net is selected that is part of more layers because the option let's you completely hide area fills and thus improves clarity. It's activation is marked by a white text in the right bottom corner of the display.

The last button together with the slider is analogous to the first one with the exception that it only works on components while the first one only worked on non-components.

All three buttons can additionally be fount in the quick menu in the top left corner of the screen.