The filter buttons filter out photographs not matching the button's criteria e.g. if you select "colour", then the "black and white" photographs won't be shown.
You can add multiple filters e.g. "colour" and "landscape"; this would only show landscape photographs that are in colour.
The sort buttons can be used in conjunction with the filter buttons; sort buttons simply re-arrange the photographs i.e. they get moved around on the grid but they do not get removed.
The clear button removes all filters but it does not remove the sorting.
The shuffle button clears the sorting as it re-arranges the photographs on the grid to an unknown order.