Why is my Galaxy s4 telling me I don't have enough space to download my emails?

[AC Question]

Email giving me a message that there is not enough space in device storage. How do I delete files? And how do I know what files to delete?

 

[Crashdamage]

To delete or move files install a file manager such as Astro, FX File Explorer or X-Plore. There's several to choose from in the Play store.

To make space you can:
Delete some texts or emails. If you really have lots, this will help.h Deal with deleting email or texts from within the apps.
Uninstall app updates.
Uninstall apps.

Android since v1.0. Linux since 2001.