To orchestrate is to design or organize something, like a plan or a project. You could orchestrate an orchestra or you could just orchestrate a yard sale.
An orchestra is a large group of classical musicians led by a conductor: it consists of many people playing together. Similarly, when we talk about orchestrating, someone is coordinating the activities of many people to accomplish something. The manager of an office orchestrates the business. A coach orchestrates the play of the team. Terrorist leaders orchestrate attacks. Orchestrating is like directing, and it applies to many more things than just music.