I guess column A: Target word or phrase B: Hint C: Surrounding phrase
The user procedure would be something like 1) highlight the target 2) Right click a context menu, 3) Left click “Add word to LingQ” (the language would be preset somehow) then some kind of dictionary pop-up would occur whereby the Hint could be added.
This would ideally go straight to LingQ but it could also just be included on a list formatted as above.