From Adobe help page
Do one of the following:
Choose File > Automate > Batch (Photoshop)
Specify the action you want to use to process files from the Set and Action pop-up menus. The menus display actions available in the Actions panel. You may need to choose a different set or load a set in the panel if you don’t see your action.
Choose the files to process from the Source pop-up menu:
- Folder: Processes files in a folder you specify. Click Choose to locate and select the folder.
- Import: Processes images from a digital camera, scanner, or a PDF document.
- Opened Files: Processes all open files. this is the most likely
Set processing, saving, and file naming options. For descriptions of the Batch dialog box settings see Batch and droplet processing options.