Bare bones explanation is that it means you are the parent the child will be spending most of their time with. You can make it so that as Primary Parent you have sole decision making on things like schooling and non emergency health issues.
My name is Rikki, and I am a psychology student - my parents divorced a couple of years ago. I experienced every side of divorce - the breaking of the news, the denial, the happiness, the fall-out...everything. Divorce practically bulldozed my family, but things improved significantly. I have many friends who endured similar changes. Children can do it pretty rough. If you need advice, I offer 'life coaching', which is honestly just advice - all from a kid's / young adult's perspective. With a breakdown of your individual situation, I can advise you on a recommended plan of attack, to assist your kids make as easy-as-possible a transition, for a better future. Because quite frankly, divorce can be crap + I could have had some advice like this in hindsight. Enquiries welcome. E - rikkiknowsthis@gmail.com