I have been unable to find what it is for. Tutorial doesn't mention Usermode 1&2.
You can add verbs, if you will. Say you want to add a smell function; all you do is set Usermode1's Standard mode property to true so it'll appear on a right click, set a nose sprite as image, then add "Usermode1 hotspot", etc. interactions.
Now you can click on stuff with a nose cursor.
You can have as many cursor modes as you want, these two are simply there as placeholders for custom user modes in addition to the interaction modes already provided. Realistically you can name every cursor mode whatever you want it to be, and use them however you want, but bear in mind that AGS, for legacy reasons, inherently depends on certain cursor modes being allocated to certain numbers. For example, IIRC eModeWait is cursor 8. You could rename cursor 8 to eModeGive if you wanted and then make cursor 10 eModeWait..but then if you ever called Wait(), instead of seeing your eModeWait cursor's graphic..you'd see eModeGive's graphic.
Also, unless it's been fixed, which I'm not aware that it has been, if you remove these placeholder cursors then you'll encounter a bug in the editor. They can be renamed, but they must exist.
AFAIK, eModeWait and eModePointer are the only cursors actually locked internally to specific interactions. The rest I believe are only called based on user scripts (including those scripts, such as the GlobalScript, provided by the templates released with AGS).
Thanks
That might come in handy sometime.