Evidence, Proof
noun
The kanji and the word are exactly the same. That means they share meanings as well.
あかし
Since this word is made up of a single kanji, it should use the kun'yomi reading. When learning the kanji, you didn't learn that reading, so here's a mnemonic to help you with this word: Your relentless search for evidence has finally uncovered the existence of a car sheep (あかし)! It's a bizarre hybrid, having a car's body but a sheep's head and legs. "Ah, car sheep! I've finally found the evidence proving you're real!"
友情の証として、このふじ山のキーホルダーをあげます。
As proof of our friendship, I'll give you this Mt. Fuji keychain.
それって、彼が君のことを大切にしている証なんじゃないかな。
That's evidence that he cares about you, isn't it?
見よ。このクリスタルこそが、王の証なのだ！
Behold! This crystal is the proof of the king's authority!