The spelling of the word "propper" is incorrect. The correct spelling is "proper". The IPA phonetic transcription for "proper" is /ˈprɒpər/. The first sound is a stressed short "o" followed by a "p" and then an unstressed "er" sound. The word "proper" means suitable or appropriate, and it is important to use the correct spelling in order to convey the intended meaning.
There is no dictionary definition for the term "propper." It does not appear to be a recognized English word with an established definition.