How do I turn off the VoiceOver 'blue circle pointer' functionality?

I often use VoiceOver, but I’ve accidentally activated an accessibility feature (via an unknown shortcut) that I can't turn off. Here's what happens:

• When I move the cursor using the trackpad, the standard cursor is replaced by a large blue circle that moves slowly (see image). The text below the cursor is read aloud automatically, so I assume it's intended as a solution for people who cannot use a keyboard or mouse.
• At the same time, the window or application beneath the cursor is highlighted, while the rest of the screen is dimmed by a dark overlay (see image).
• Both the cursor and overlay disappear when I stop moving the cursor.
• This only occurs when VoiceOver is enabled.

My questions:

1. Where can I turn it off? I've searched everywhere in the Accessibility, Pointer, and Trackpad settings without success.
2. Optionally, what the name of this functionality and what is it for?

Thank you.