SRID is a unique number referring to a particular co-ordinate system; {% if country == 'GB' %} the ones you probably are interested in are 27700 for British National Grid, 4326 for WGS84 lon/lat, and 29902 for the Irish National Grid. {% else %} the one you probably are interested in is 4326 for WGS84 normal lon/lat. {% endif %}
x and y are the co-ordinates of the point in the co-ordinate system; note that x,y means longitude,latitude.
A hash of the areas that the point is contained within. If the /box version is used, only the area bounding boxes are considered.