Basically it says that meat products from the USA are prohibited because of BSE (mad cow disease/hoof and mouth disease) and fowl meat products are prohibited from about a dozen different countries because of the outbreak of bird flu.
Ah, so it's an airport customs sign, now I know, thanks! On one aussie news site it was featured in the gallery of funny photos entitled "A somewhat disturbing sign our reader saw after eating in a Japanese restaurant ..."
Thanks!