What does archival contribution in journals mean? When I submitted my manuscript for publication in a journal, the editor rejected it with the comment "not enough archival contribution".

Please help me by saying what he meant.
Presumably, he simply meant that your paper does not have enough long-lasting contribution to your field of study. That is, there either is too little contribution at all, or the editor assumed that your paper only has a very temporary contribution which will be outdated soon.