There are a few problems with this notice. First, the plural form apparels is wrong, since the word apparel is uncountable in Standard English (for this reason we don’t normally say some flours or some milks).
Second, Less Up To 20% is a non-standard way of saying Up To 20% Less. The writer was probably translating directly from Chinese, using the word less as a verb (as in Mandarin kòu 扣).
Finally, I’d change regular priced items to regular-price items.