翌 is a bound form (黏着语素) used in formal or literary Chinese to mean 'next' or 'following', almost always before a time word like 日 (day), 年 (year), or 晨 (morning). You cannot use it alone — it must attach to a noun to form a compound like 翌日 ('the next day'). It's more common in written news, official documents, or classical-style prose than in everyday speech.