Basic overview, it is French Fries with cheese curds, which are covered in gravy. Ideally the gravy is hot enough to melt the curds onto the fries.

Here (Canada) almost all fast food chains (even American ones) will sell this item. There are even specific restaurants for it, with specialty poutines with different ingredients and gravies. It is also very easy to make home made with your own gravy.
There are some who don't like it but it is generally a very popular item all over and is one of my favourites.
So I ask, have you even heard of this food before now? Would you be willing to try it?