Half
prefix, suffix
The kanji and the word are exactly the same. That means they share meanings as well.
Since this word is made up of a single kanji, it's supposed to use the kun'yomi reading. But, there is no useful kun'yomi reading for this kanji, so even the single kanji vocab word version uses the on'yomi reading, which you've already learned!
一才半
one and a half years old
一分半
one and a half minutes
二メートル半
two and a half meters
JLPTまで、あと一日半しかないよ。
There's only another day and a half until the JLPT exam.
この子は三才半です。
This child is three and a half years old.
このキッチンの大きさは、およそ二メートル半です。
The size of this kitchen is about two and a half meters.