Options

Close Holes

Remeshes over the original's holes (open borders): each is capped in the copy the engine gets, so the result is closed. The original is not changed. For scans with gaps, or a sculpt with an open neck you want closed.

Off	On

Keep Attributes

Carries the original's vertex groups, UV maps and colour attributes onto the result (from the nearest face, interpolated), so a rigged or painted mesh stays usable. UVs that cross a seam of the original want a re-unwrap there.

Show

Overlays in the viewport, on the result:

Toggle	Shows
Poles	A dot on every vertex where other than four edges meet: blue 3, orange 5, red 6 or more.
Density	Each quad tinted by its size against the size asked: white as asked, blue smaller, red larger.
Verdict	The active result's one-line verdict, bottom left: clean or not, quads, poles, time.
Bands	The bands your guides cut the mesh into, each in its own colour, on the original before the remesh and on the result after.
Regions	While drawing: the regions between the guides, tinted by the patch each fills as (with Fill Between), with about how many quads each gets.
Sketch	While drawing, with Fill Between: the rows of quads each grid, pole patch and ring will get.
Advice	Where the engine had to add a line to your drawing, or found a band it fills badly. Where the fill failed is marked red even with Advice off.
Key Card	While drawing: the keys for what you are doing, in the viewport's corner.

Light red on flat parts and blue on ears and fingers is the curvature adaptivity at work; a bright red patch on a detail is where to paint density.