The word is, the verb “to be” doesn’t really mean what people think it does. It means that something matches a metaphor, or is well modeled by a concept. For example “this is a car” really means “this thing here seems to be best modeled by the concept of ‘a car’.” Think about why that is. It’s because there is no such thing in the real world as “a car.” Is it possible for you to imagine “a car” (as in a car that has only the purest qualities shared by every car)? No you can’t imagine it because it doesn’t exist, you can only imagine specific cars, a big red car with a sunroof and 2 doors, a small green car with fancy rims and 4 doors, etc. There is no such thing as a car, only types of cars. So saying “this is a car” does not mean this is a car, it means this would be best described as a car, but really it’s a lot of things and I have no idea what it “really is.”