Howbeit. But, or And yet.
this man. this one.
when. whenever.
cometh. may come.
whence He is: i.e. how He may come. The Rabbis taught that He would come from Bethlehem and then be hid, but none knew where. See Lightfoot, vol. xii, pages 303-4.
Related Commentaries of John 7:27
John 7:27
27 Howbeit we know this man whence he is: but when Christ cometh, no man knoweth whence he is.