Mediation is a process by which parties who can’t reach agreement on their own involve a third person to help them reach agreement. It could be two siblings asking their grandma help decide which movie to see, a divorcing couple hiring a mediator to help them avoid litigation, or management and union of a large corporation asking a former government official whom they trust to avoid a strike.
What all mediations have in common is that the third person is trusted by all parties and that this person does NOT have any power over the parties to force them to agree to something they don’t want. In the grandma example, in order to be a mediator, she would have to be indifferent to what movie the siblings choose - her goal is to help them decide something that would work for them.