I didn't know about beeves

I thought it's single form was its plural form, like sheep or fish.

How would you use the word beeves in a sentence?

for some reason this ….. makes me VERY happy

I'm a beef

We are beeves

It's from Oxford Dictionaries. And the "sense 1 of the noun" refers to "A cow, bull, or ox fattened for its meat". In this sense, of course it is countable. But it is still uncountable when 'beef' means meat :-)