that is my understanding at a high level.
Basically you need a certain level of subscribers and views before your videos are "monetized".
However if you have certain things in a video (e.g. Copyrighted music) it gets "de-monetized".
If you ARE in the money-earning category, when Youtube shows an advert, you get a share of the revenue Youtube earned from, the advertiser, but only if advert is allowed to play for at least a minimum time (which I think is 10 seconds).
As an aside, Youtube is owned by Google (well, actually Alphabet) and they control and manipulate all this to Youtube Creators to maximise their (Youtubes) profits. Just the same as they frequently do to sites showing Google Adverts, and will often cancel a sites revenue rights just before a payout (they did this to me a few years ago and you have no right to appeal).
because of all these variations, the only people who know how much a channel earns is Youtube and the channel themselves. One thing for sure, it is not as much as people imagine!
Here is the info for TravelTrolls -
https://socialblade.com/youtube/channel/UCd2_Z8IE9V2THqtdzNVQsIg
View attachment 85972
At a guess, I would think it will be significantly towards the lower range as most people skip ads (I certainly do!) and Youtube randomly de-monetize a channel for no reason.
So some handy pocket money for sure, but not an income.
I don't think earning any kind of living from Youtube is very commonplace at all and for individials is pretty well limited to people who actually put a hell of a lot of work into the videos or happen to hit a certain sweetspot (like the 6 year old whose parents post toy reviews).