ℹ️ This feature is available to all users.
The key to precise sketching and modeling is dimensions. Any sketch or body you create will have a dimension label attached to it. You can select the sketch and then the dimension label, and adjust the value in the numpad on screen or on your keyboard. While you’re sketching, you can directly type in the value and press the Return key to finalize the dimension.
These are the dimensions:

Length
The length of a line.
You can also change the distance between two points—by selecting them and entering the desired length (absolute, horizontal, or vertical)—or a point and a line. 
Radius
The radius of a circle or arc.

Angle
The angle of an arc or the angle between two connected curves.
To change the angle between two connected curves, select the two arcs or lines.