Which way is the arrow pointing?
In Japan, it's rude to point at people with your finger.
Oh, you’re color blind, eh? So that means you can’t point at which one is red and which one is green, then.
The kanji means finger. So, if you "to finger" something, what are you doing? You're pointing. That's why this word means to point.
Since this word consists of a kanji with hiragana attached, you can bet that it will use the kun'yomi reading. You didn't learn that reading with this kanji, so here's a mnemonic to help you:
You are pointing at something in fear. It is a saw (さ). Thing is, you're pointing at this saw with a missing finger. It just cut off your finger and you're freaking out, trying to point with a bloody non-finger.