TRP3 has some limited help located on their Curseforge project pages (some videos and links on the right):
https://wow.curseforge.com/projects/...ages/tutorials
And a documentation site that mostly covers the addon/Lua part:
https://totalrp3.info/documentation
After looking through the first link, I believe there's a variable setting option according to the comments, which had
this image. You then should be able to call your own variable using ${variablename} in a later step. For example, the variable in the linked image should be able to be accessed using ${positionX}.
With that said, as others pointed out, this is custom coding and not how addons work. Only TRP3 uses stuff like this. If you intend to mess with addons in the future, be sure to forget, or at least not focus on, what you've learned making TRP3 campaign stuff.