1. Add your images under /var/import/images/product_images
 2. Add this path in the images file directory field during upload the file
[![Images fiel directory fiel][1]][1]


  [1]: https://i.sstatic.net/ddTmQ.jpg

Magento's default directory is var/import/images.

If you are uploading images under var/import/images directory then no need to mention directory path in the "Images File Directory" field.

If you have any questions please let me know.