twenty
廿 represents the number twenty, specifically two tens combined into one character.
廿 is a ligature of two 十 (ten) characters stacked vertically, representing twenty.
Picture two tens (十) stacked together: the top 十 and bottom 十 merge into 廿, making twenty.
For ジュウ, imagine a jeweler counting twenty gems: jew -> ジュウ, and the twenty gems are neatly arranged like the strokes of 廿.