The group of squares in the upper left corner of the window represents the sides and corners of the bounding box of the current selection.
Click on one of the small squares to select it, and it will then become black. The X and Y values then indicate the coordinates of the respective center, side or corner point.
Enter a new value for Width or Height to resize the selected objects relative to the current point. Confirm the respective values with the Enter key.
Then close the dialog box with the x symbol in the upper right corner to apply the values.