suffix, counter
counter for leaves, sheets of paper, etc.
Used for flat, leaf-like objects: leaves, sheets of paper, photographs, etc. Attaches to numbers.
この木には何枚の葉がありますか？
How many leaves are on this tree?
書類を三葉コピーしてください。
Please make three copies of the document.
suffix, counter
Archaic counter for boats; modern Japanese uses 隻 (せき) instead.
古文書には「舟三葉」と記されている。
In old documents, it is written as 'three boats'.
隻 is the modern counter for boats and ships, replacing the archaic use of 葉.
From the noun 葉 (は, leaf), extended to count flat, leaf-like objects. The reading よう is the on'yomi.