Yeah I don't know. Like I get it at a conceptual level.

It basically says that they work out the fertility rate by dividing the number of women by the number of babies. They say they do it in 5 year blocks, I guess this accounts for say lots of kids or lots of old women skewing the numbers when they don't have babies.

As for why we have 38,000 deaths and 59,000 births and this is below the replacement rate, I start to feel like I understand but then decide I don't. The best answer I've found is a suggestion that births per women below 2.1 doesn't necessarily mean a shrinking population, because of the distribution of women of various ages may mean many women of childbearing age (say, through immigration) can cause the population to grow despite births per women being below 2.1.