Components are an integral part of react. Every part or a react app, from an individual list item, to the app itself is setup as a component. there are a few ways to think about the structure of a component, and your major choices are: Class Component, or Function Component. React Docs on Components and Props
the render function is made to determine what should be rendered to the dom, when the component is used. you should use a return block to set what will be returned from running render. This function is a requirement of a Component.