A year of yojijukugo! I’m as amazed as anyone, believe me.
Literally: bountiful – year – full – make
Alternately: A bumper crop; an excellent (rice) harvest.
Notes: One may be tempted to write man as 万; this is incorrect.
Note that the two halves of this compound, 豊年 and 満作, have similar meanings. Just as 恐怖 (“fear fear” = “fear”) or 恋愛 (“love love” = “love”) combine characters with similar meanings into one word, so does this four-character compound combine two words into a single unit, and emphasizes the idea it’s trying to express as a result.