expression, noun which may take the genitive case particle 'no'
first and last; one and only
Emphasizes that something is both the first and the last occurrence, often implying it is a unique, never-to-be-repeated opportunity or event.
これが最初で最後のチャンスだ。
This is your first and last chance.
彼にとって最初で最後の恋だった。
It was his first and last love.
A set phrase composed of 最初 (first) + で (and) + 最後 (last). The literal meaning is transparent.