It says: Prices will show at the end

This is not an error. The App Store has not sent the prices yet. Go on with the next screens. The prices show on the last screen.

Logging one baby by hand is free. The Family plan is $11.99 a month, with the first month at half price, or $79.99 a year, for the whole family. Prices are in US dollars. In other countries, the App Store shows the price in your currency.