Chapter 6 is devoted to the processes that Freud calls the "dream-work"—that is, all of the mechanisms and modes that dreams use to combine, censor, or communicate their contents.
Freud repeats his argument that the true task of dream interpretation is to discover the relationship between the "manifest" (surface-level) and the "latent" (below-the-surface) content of dreams.
Freud calls the "manifest" content the "dream-content" and the "latent" content the "dream-thoughts"; he says that the relationship between these two is "like two versions of the same subject-matter in different languages" (6.1.2).
Freud goes on to finesse that argument, declaring that the "manifest" content of dreams is like picture-puzzles. In order to interpret it, we can't take the pictures literally: we need to determine what other syllables, words, or ideas they represent.