Externally link to an image folder

What does link mean ? Inserting the image directly from image url ?

sorry i mean using a folder on our website as a sort of online image library, which emails that are sent out to external customers ‘link’ to and use the images.

Does this make sense?

Yaa you can do that. You can check this for more detail https://www.wpbeginner.com/beginners-guide/how-to-get-the-url-of-images-you-upload-in-wordpress/ it is shown in old admin but applies in new one too ??