This function allows you to convert and edit multiple files at once.
in the main menu select File -> Batch Conversion...
Choose the folder on disk where the source images are located, then select any images holding the Ctrl key. Or select them all by clicking the "Select All" button.
Choose the Destination folder and the output format.
If you want to apply some editing/adjusting functions to the images, please use corresponding options.
When you are ready, click the "Start" button.