Older Sister, Big Sister, Elder Sister
noun
The kanji and the word are exactly the same. That means they share meanings as well. This is your older sister, by the way. Not somebody else's.
あね
Since this word is made up of a single kanji, it should use the kun'yomi reading. You haven't learned this reading yet, so here's a mnemonic to help you remember: Picture your older sister (even if you don't have one), her birthday is coming up and there's only one thing she wants from you. A necklace (あね). She's wanted a necklace for years and you're finally going to give her one. She'll be so happy.
姉はシンガポールにいます。
My sister is in Singapore.
姉のお父さんと私のお父さんは同じ人です。
My sister's dad and my dad are the same person.
二人の姉と、一人の兄がいるので、四人兄弟です。
I have two sisters and a brother, so we are siblings of four.