Wikipedia took one hundred million hours of volunteer time to create..... How do we measure this relative to other uses of time? Well, TV watching, which is the largest use of time, takes two hundred billion hours every
houryear---in the US alone. To put this in perspective, we spend a Wikipedia worth of time every weekend in the US watching advertisements alone.
You copied the quote wrongly, the correction I've made makes a big difference, although trying to make the maths work still makes my head hurt so I'll move on.
The passage seems to be saying that every weekend in the USA, the number of hours in total that the population spends watching TV advertising is comparable to the number of hours that was spent by volunteers to create Wikipedia.
not a teacher