Select the 'Automatically orientate images using Exif tag' if you want Image Orientate to automatically orientate the image based on the Exif orientation tag value stored in your images. Image Orientate will also update the tag to reflect the change.
You also also manually change the orientation of the image using the 'Apply the selected orientation setting' option. You can flip the images along the horizontal or vertical axis, or rotate the images in 90 degree increments.