St. Augustine describes the process of learning language as associating names with objects. This picture of language suggests that every word has a meaning and that sentences are sets of names. Such a picture of language disregards the different kinds of words. For instance, imagine a language-game where someone writes "five red apples," and shows it to a grocer. The grocer makes different uses of each of the three words in filling out the order: "apple" directs him to a particular fruit, "red" leads him compare the fruit with a color, and "five" tells him how many fruits to count out. We haven't explained how the grocer knows that "red" is a color or what the meaning of "five" is; we have simply described how these words are used. It is not yet clea r what such explanations would look like.
Augustine's picture of language may seem adequate for a simpler language than our own. We can imagine, for instance, a language between a builder and his assistant that consists only of the words "block!" "pillar!" "slab!" and "beam!": the builder shouts one of these orders and his assistant fetches the object he names. Children learn by ostensive teaching what these different words name and are trained to obey and give orders. We should not say that the ostensive teaching creates an understanding of the words in question, because it can only be said to do so in the wider context of the training: teaching and understanding cannot be examined in isolation.
In section 8, Wittgenstein considers a complication of this language-game, introducing number-words, color-words, and "this" and "there." We can teach these words by pointing and speaking, but the manner of teaching will be very different depending on th e kind of word being taught.
We may be tempted to generalize about all words, since they all look alike, but such generalizations are useless. We might say, "every word in language signifies something," but what we say they signify depends on what sort of distinction we are making. W e might say "one" signifies a number if we want to distinguish it from "slab!" or we might say it signifies the first cardinal number if there is some confusion as to the order of number-words. All questions of what a word signifies come back to how that word is used, and words are used in unlike ways.
These language-games are not incomplete. They simply have a smaller scope than ordinary language. Every language embodies a particular form of life that is complete in itself.
Wittgenstein asks if "slab!" in this language means what it does in ours. We can shout the order "slab!" but we might say in our language this means, "bring me a slab," whereas the words "bring me a" do not exist in the builder's language. However, how d o we know that "slab!" means, "bring me a slab"? How do we mean the four-word sentence while uttering the one-word command? We only mean, "bring me a slab," as opposed to other sentences that involve the word "slab": "hand me a slab," "bring me two slab s," etc. This contrast exists in our language not because of any mental act of meaning, but because our language contains the possibility of different forms of expressions. If "slab!" means the same as "bring me a slab," this is not due to any mental act of comparison, but simply because the two expressions are used in the same way.