This text component is used to add standard copy to webpages. Pages created in the new design system templates include an R45 - TextComponent already added. This is the main text component for the page.
It is important to note that for every component that you add, you need to add another R45 - TextComponent if you want to include more text.
You would add these like any other component, creating a new content item in the relevant datasource folder. If you have multiple text components per page, it is useful to number them so they are easier to keep track of.