It is assumed that you have already uploaded some files. To make edits to more than one file at a time, click the box next to each image to be edited, or click the box at the very top to select all images.
Selecting an image will also enable the red 'Delete' button, which allows you to remove one or more images at the same time. You'll be asked to confirm your choice prior to removal.
For a bulk edit, select multiple files at the same time.
Click the small cog wheel below the upload button in the top right corner. A "mass edit" button will appear.
Click "Mass Edit". A modal will open with actions that can be applied to multiple files at once:
To either exclude or include multiple images from the Media Library, click the 'execute mass edit' button on top.
To copy changed titles, descriptions and categories of images to all other languages, click the 'execute mass edit' button at the bottom.