Three related tools control attention: blur hides, shape masks frame, and the spotlight dims everything except the part you point at.
Blur a region Effects → Blur can soften the whole frame, or only a rectangle or ellipse you drag over a face, plate or logo. The region stays put for the clip's duration.
Crop to a shape Effects → Mask crops the clip to a rounded rectangle, ellipse or circle, with an edge feather for soft borders. It suits overlays and insets.
Aim a spotlight The Mask editor's spotlight dims the frame except a highlight you drag into place. Size, feather and darkness are adjustable, and a large centred one is a classic vignette.
Combine Masks apply to the composited layer, so they work on full-frame clips and floating overlays alike, and they persist through transitions.
Tips
The spotlight is how you point at one thing in a busy screen recording: dim everything but the button.
Feathered circle masks turn any clip into a clean webcam-style bubble.
To remove a region rather than hide it, use the eraser: it makes the area transparent instead of blurred.