Old Age
noun, の adjective
If you are at an elderly age you are at an old age.
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
日本の老齢年金の仕組みについてご説明してもらえませんでしょうか。
Could you please explain the structure of Japan’s old-age pension to me?