Plugin for managing texts separately

Hello!

I am looking for a plugin in which to manage texts separately. I want to limit my clients access to the site (due to ease of access) and since a lot of the site structure is definied in the Pages section I don’t want them fiddeling around there if they want to change a text.

What I am looking for is something that lets you keep the text editing in a separate plugin and which generates some kind of referencial code (like a shortcode with a getText function) that you would paste into the site structure. This means that when someone alters the text within the plugin, the referenced text area would change without the user having to visit the Pages section.

Does anyone understand what I am looking for? Is there any kind of plugin like this out there?

Thanks in advance!