Mediation is a part of alternative dispute resolution (ADR), wherein disputes/conflicts are resolved out of the court. It involves a step-by-step interactive process in which a neutral mediator uses specialized communication skills to help conflicting parties resolve their dispute through negotiations. 

Unlike in arbitration, a mediator does not make decisions for the parties, pass opinions on the merits of a case, or determine what is “right” or “fair.” Instead, a mediator tries to bridge the opposing interests of the parties involved and attempts to facilitate a negotiated settlement between them.
A mediator also guides and moderates the negotiations so as to avoid any confrontation between the conflicting parties.

A mediation session usually for a four (half day)  or eight (full day) hour session. So the parties taking part in the mediation process should be prepared to spend at least that much time. However, if the dispute isn’t resolved within the said time, the parties may have to schedule another mediation session to carry forward the negotiation. Apart from that, the mediator would prepare an agreement after the parties reach a settlement, which takes additional time.

After a settlement is reached through mediation, it is followed by an agreement which can be either oral or written. Whether or not this agreement is legally binding depends on the law of the local jurisdiction.
However, within the US, most of the post-mediation agreements are considered legally enforceable. Also, in certain court-ordered mediations, the final agreement is considered a court judgment.
In cases where no agreement is reached between the parties, either party may decide to pursue the case in forums such as courts.