If you reach an agreement in mediation, the mediator (or the attorneys and the mediator) will write an agreement. You and your soon-to-be ex will then read and sign the agreement.
(Note: this is how it usually goes. There are some situations in which people don’t want to sign during mediation and want to take a few days to think about things. The main problem with this approach is people start trying to change things after mediation, which never works well, and you end up not signing the agreement.)
If you do negotiate and sign an agreement during mediation, you have to assume you will be bound by that agreement.
Attempting to change a signed mediated settlement after you have agreed to it in writing is very difficult. Usually, forcing the change of a mediated settlement can only be done if someone committed some sort of fraud during mediation, and you would need to go to court to force a change.
After an agreement is signed, your case is effectively finished.
Your family law attorneys will put together a few documents the court requires so the judge can sign the final documents, but you won’t need to go to court. When the judge signs everything, you’ll be done.