Fact
Factual, In Fact
noun, adverb, の adjective
The occurrence of truth is a fact.
事実 is primarily used as a noun, but it can also be used to say something is factual. Additionally, in relatively formal writing it can be used as an adverb to mean in fact.
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.
以上は、全て事実です。
All of the above is factual.
この本には、数学にまつわる事実がたくさんのってます。
This book has many facts about mathematics.
全日本の人々が知っている事実だが、北海道のカニはおいしい。
It's a fact that all Japanese people know, but crabs in Hokkaido are delicious.
父は事実、それを知っていました。
Dad, in fact, knew about that.