。
A tree is known by its fruit.
Literal
Tree [topic-は] its fruit [by-means-of-によって] is-understood.
An alternative rendering of the same proverb using the formal compound particle ~によって ('by means of, through, by') instead of the conditional. ~によって is a fixed written/formal alternative to で for marking means, cause, or agent, especially common in essays, official language, and translations from European languages. その is anaphoric 'its' (referring to the tree).