The @gallery directive generates a thumbnail gallery on a page where the thumbnails can be clicked on to show a larger version of the image.

So for example the gallery example source file has:

@gallery
../../apple.jpg This is an apple
../../avocado.jpg Do you like avocados?
../../guava.jpg It's a guava
../../lemon.jpg I like lemonade
../../orange.jpg Naranja in Spanish

The images to display in the gallery are listed one per line after the @gallery directive, with a description of the image following the image filename.