The measure commands allow you to see temporary measurements related to your project
When in need of a distance between two points, Measure Line can be used by clicking once to establish the base point, and then a second time to retrieve your distance.
Additionally, after the initial click, you can input a numeric value to lock your desired distance in place to verify specified distances.
With the Measure Circle command enabled, click once to set the middle of your circle, then drag your mouse outwards to establish the radius of your circle.
The same function of typing in a number after establishing the center of your circle applies.
By establish at least 3 points, the area of your defined space will appear in the middle of your polygon shape. Enable the Measure Polygon command, and begin defining your area by clicking the extents of your desired location.