Truth
Fact, Reality
noun
The action of truth is just truth itself, though it's also facts and reality as well. Really, it's the idea of "truth" in a way.
じじつ
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.
事実かもしれないけど、なっとくはできないな。
That may be true, but I'm still not convinced.
あのせいじ家の言っていることは、事実に反します。
What that politician has been saying contradicts the facts.
口髭を生やした男が気味悪く見えるのは、科学的な事実です。
It is a scientific fact that a man with a mustache looks creepy.