is both plural and singular.
There is a group of words in the English language that are "uncountable" - in order to count them, you have to use a "counter". Food is one of them. Water, juice, wood, air are others.
In order to count these things (and make them singular or plural), they either have to be grouped into some countable "container" (baskets of food, glasses of water or juice, canisters of compressed air etc.), or you can use the words "some", "much" to describe them.
The way to find uncountable nouns is to see if you can "count" them without any other "container" between the number and the item:
"Two Cakes" - this word is countable
"Two woods" - not really. It would be better to say "One piece of wood". This word is uncountable.
"Foods" can be used when referring to different kinds of things, but it is a much less common usage.
Does this help?
__________________________________________English Tutor for ESL Students in Victoria BC
Your source for language and academic help.