Wittgenstein's statement, "The limits of my language are the limits of my world" is in a certain sense a repetition of the starting point of the Tractatus: "The world is all that is the case." This starting point is enriched by the findings of section 5, in such a way that the world interpreted in section 1 as a free indirect discourse now shows itself to be identical with a world that I call "my" world. This enrichment comes about by way of what is original in the treatment of truth-functions.
It is a condition of complex truth-functions that the arguments which are to be comprised by the range of the function should be of the same type. They could not otherwise indifferently determine the sense of the function. If we are to reach the result that a truth-function says something, it must also be a condition that the arguments are either elementary propositions or can be analyzed into elementary propositions. It follows from these conditions that elementary propositions are of the same type as the complex propositions which are supposed to have been constructed out of them by the addition of 'logical constants.' Elementary propositions are already truth-functions of themselves. This claim is easy to overlook and hard to swallow, but it is the heart of Wittgenstein's logic.
If all propositions are of the same type, then there is in fact only one type: what is the case, that is, the parts of the world. It is necessary that the world which is the totality of these facts (not a whole greater than them but "divid[ing] into" them) would itself be constituted of the same type as that of the arguments of truth-functions. The world is not something 'about which' propositions are formed. If it were something beyond language then it would also be beyond language to say anything about the world.
It is characteristic of free indirect discourse not to present itself as such. Likewise the world does not come with quotation marks around it. Yet, we "picture facts to ourselves." In other words, we say the world to ourselves. The self thus simultaneously disappears from the world (realism) and becomes its limit (solipsism).