Since the 1990's, Photoshop filters have appeared in ever increasing numbers, and there are probably now 3000 or 4000 filters available. This collection brings together a wide variety of different filter plugin effects from super professional to more humble plugins such as the Filter Factory Filters. Each plugin works in a different way so you have to check the documentation which comes with each one.
In most cases, you can undo any changes you make using a certain filter in photosshop so the best way is just to experiment. Try the plugin with different images and different settings. Or siimply use the plugin in combination with other effects or actions. As with all things, it depends on what you would like to achieve using the plugin and the capabilities of the plugin and how much time you have to create that perfect image. Most of these plugins come with preview screens so you can modify the sliders without affecting the main image. These plugins are really aimed at professional photographers but you can also have fun just experimenting.