Where do we use the words food and foods?
The noun 'food' is a mass noun (an uncountable noun).
The plural noun 'foods' is a word specifically for 'types of' or 'kinds of' food.
The noun 'food' is a type of mass noun called an aggregate noun, a word representing an indefinite number of elements.
A partitive noun (also called a noun counter) is a noun used to count or quantify a mass noun (a lot of food, a bit of food).
An adjective (or determiner) can be used to quantify a mass noun (some food, no food, hot food).
The plural noun 'foods' is used in the context of:
The menu listed a variety of Asian foods.
The foods displayed in the stalls all looked so tempting.
James only cooks foods that he can microwave.
I've pretty much had to give up fried foods.