A postposition is the equivalent of a preposition in languages where the preposition appears after the noun (such as Japanese). Here are some examples:
Hungarian: kutya nélkül dog without
Japanese: doko ni where at, doko e where to
Korean: Hanguk e to Korea
English has one postposition: ago, although in everyday speach, some prepositions are used as postpositions. Do you know what I'm getting at?