Batch is your ability to perform a certain task in Joomla with a batch of multiple items in one go. It's called "Batch processing".

You may find the Batch button in various administrative pages in your Joomla control panel. 

• Go to Content > Articles. 

You will see the Batch button located in the top right corner:

• Select one or more of your Joomla articles and click on the Batch button. You will see the "Batch process the selected articles" box:

Here you can perform the following tasks with the batch of your selected articles:

• Set their language
• Move or copy them into a selected category
• Set their access level
• Add tags to them.

Joomla also provides you similar batch processing capability for your categories, menu items, and users.

As you can see, batch processing is a fairly simple task. You just select the items to batch process. Then you select what particular action you would like to perform on them. And finally, you click the Process green button. It's that simple.