Mom gets 3 weeks before birth, both gets 15 weeks each, and 16 weeks can be distributed as parents see fit.
So if mom gets the full 16 weeks, she gets 34 weeks total, and partner gets 15 weeks.
Parents can decide to get 80% pay, in which case they get 61 weeks total.
Some weeks around birth is fixed, apart from that parents can decide how to use it. One could work two days a week and have three days off, for example.
The pay is capped, but many employers will compensate the difference for high earners.