Batch Rename FIles

Or, in plain English, rename loads of files at once.

So you have a load of files, maybe images or video, with obscure, automated titles like IMG123456 and so on, but you want them to have titles that are at least reasonably related to the English language.

Well there is a tool for this on your Mac, here's how you do it.

You only have to set this up once, then you can use it forever...

1. Open the App called Automator and create a new workflow file (press Command-N or choose New from the File menu). Then choose Service from the window of available workflow types (this option will look like a gear).
2. Adjust Service inputs - so be sure to choose "files or folders" from the first drop-down menu at the top of the workflow, and then choose Finder from the second menu. 
3. Drag the Rename Finder Items option from the action library (to the left of the window, under the Files & Folders category) to the workflow window. When you do this, Automator will issue a warning that this action will alter existing files, and provide you with an option to add an action to first copy the files instead of altering them. At this point click Don't Add.
4. Under options click 'Show his action when the workflow runs" so you have the choice to decide what and how you wish to rename the files (See example below).
5. Save - name it something like 'Rename Files'
6. Now when you go to the Finder, you can select a group of files or folders, and then right-click them and select your workflow from the Services submenu of the contextual menu.

https://kkaefer.com/journal/2011/batch-rename-on-lion/