Geometry panel
With any selection that has a bounding box

The sun selected and the Geometry panel: position, size, rotation, scale and the reference point

When it appears

With any selection that has a bounding box. Where it is and how big it is.

Fields

FieldWhat it does
PositionX and Y of the point selected on the reference point locator, from the page origin; when you type in one field, only that axis moves
Sizewidth and height. The button before the numbers keeps the proportions: with the constraint on, the field you type in drives the other
Rotationthe angle, around the locator point
Scalea command, not a measurement: it always reads 100%, and typing "150" (or "150%") scales by 150% around the locator point
9-point reference point locatorwhich point stays fixed: it applies to size, rotation and scale, and it is the point whose X and Y you read. The box inside it rotates with the object
Each onewith several objects: scale and rotate each one on its own bounding box instead of the shared one

In the header

The two reflect buttons: horizontal and vertical, with ⇧ each object on its own center.

One or more objects

With a single object you read and write in its own space: on a rotated object the size is that of its sides. With several objects, in the shared bounding box, unrotated.