Hi Ken,
Burning something is great! ‘Burned items’ are radicals, kanji and vocabulary that you have reviewed (and gotten correct) a LOT of times. Enough times, in fact, for the WaniKani (SRS) algorithm to deem you not to have to review them anymore. However, I believe there is an option for you to remove an item from being ‘burned’ if you believe you don’t know it well enough yet.
Review timings for kanji and vocabulary are 4h, 8h, 1d, 3d, 1w, 2w, 1m, and 4m. The ones that are a day and longer are actually shortened by an hour (but close enough). Therefore, the minimum time for burning an item is 5m 3w 4d 12h, assuming you review as soon as it’s available and get every review correct. That means that once you ‘burn’ something you should probably remember it for good.
I’m fairly new to WaniKani though and there is every chance I’m not quite correct, so take my reply with a grain of salt.
I can honestly tell you that I’d have fail to answer a ton of the items I’ve burned - because some of those happened 3 years ago.



