GraphQL is an alternative to REST when it gets to the communication with an API, particularly useful for frontends. 
It is sometimes just summarized as "SQL in JSON over HTTP" and even though that description is not really a lie, GraphQL is more than that.
It may reduce bugs, as it introduces type safety to the communication with your server, which can be powerful if you are using TypeScript (or another typed language) in your frontend.
With the increasing importance of performance for single-page applications, reducing the bandwidth in the API communication becomes more important. 
By giving the frontend the responsibility to decide which data should be loaded, reducing bandwidth becomes more feasible and safer.
As you subscribe to changes with GraphQL, you will not need to implement manual polling your application, which will also improve the perceived performance and usability of your application.
We will introduce you to the basics of GraphQL as well as show you around the great tooling that exists in the React ecosystem to get started with GraphQL as fast as possible.