the prose consists of writing that does not adhere to any particular formal structures other then simple grammar "non-poetie writing,perhaps.
the term sometimes appears pejoratively, but prosaic writing simply says something without necessarily trying to say it in a beautiful way,or using beautiful words.
prose writing can of course take beautiful form, but less by virtue of the formal features of words.
rhymes, alliteration, metre, but rather by style, placement, or inclusion of graphics.