This is the Invoice tab of the Visit Editor.
[Careful observers will note that this is a screen shot from a system using a modified label for the Find button and right justified field labels.]

The buttons at the bottom are:
Apply - save any changes but do not close the Visit Editor
OK - save any changes and close the Visit Editor
Cancel - cancel any changes and close the Visit Editor
Completed - save any changes, set the Invoice Status to Completed, and close the Visit Editor
In Progress - save any changes, set the Invoice Status to In Progress, and close the Visit Editor

This screen works in a very similar manner to the Customer|Charges|Invoice edit screen - see this for more information.