noun, used as a suffix
Familiar suffix attached to a name or title to address or refer to an older sister or a close older female figure. Used in casual, affectionate contexts.
花子姉、ちょっと手伝ってくれる？
Hanako-nee, can you help me a bit?
お姉ちゃんは優しいねえ。
My older sister is so kind.
Derived from the older sister term あね, with sound change to ねえ in familiar usage. The kanji 姉 is used for its meaning 'older sister'.