Partzuf is a Talmudic word borrowed from the Greek prosopon, meaning either "face" or a mask that covers the face (in Greek it eventually came to mean "person" as well). Hebrew already had the biblical word for face, panim פנים, and so partzuf went through a number of transformations. In Talmudic literature the two words were more or less synonymous, but later in Hebrew it began to take on a negative one. (Panim can be used for the face of any physical object, whereas partzuf is only for a human face). So today partzuf generally has less a positive connotation, and so you might tell a child not to make a face - לעשות פרצופים le'asot partzufim or partzuf atzuv פרצוף עצוב - "sad face".
In any case today the sense of "face" is almost always associated with some description, and as such has also come to mean "characterization, personification", and through a process called metonymy, where an attribute is substituted for the thing meant, we have in Israeli slang the use of partzuf without any description to refer to an ugly or negative person. Eizeh partzuf איזה פרצוף - "what a (bad/ugly) guy!"
The etymology of prosopon goes back further than Greek. Klein writes that it literally means "that which is toward the eyes", from pros (= toward, to, against) and ops (=eye, face). Pros is related to the prefix pro, also meaning "before, in front of, sooner," and is the root of dozens of English words. One of them is "from", which originally meant "a preposition denoting departure or movement away in time or space" and also the word "frame":
Old English framian "to profit, be helpful, avail, benefit," from fram (adj., adv.) "active, vigorous, bold," originally "going forward," from fram (prep.) "forward; from". Influenced by related Old English fremman "help forward, promote; do, perform, make, accomplish," and Old Norse fremja "to further, execute." Compare German frommen "avail, profit, benefit, be of use."
Sense focused in Middle English from "make ready" (mid-13c.) to "prepare timber for building" (late 14c.). Meaning "compose, devise" is first attested 1540s.
The German cognate mentioned in that entry, frommen, has a related word in German - fromm, meaning "pious, devout" (via the senses of "good, righteous".) And from here we get the Yiddish word "frum".
Quite a journey, no? Things aren't always what they seem - a partzuf might be a face, or it might be a mask, and don't get me started on knowing whether or not someone is actually frum...