Learn Hardcore Latin: Lex clara est, et omnes sciunt iura civium servanda esse. - The law is clear, and everyone knows that the rights of the citizens must be preserved.

Breakdown of Lex clara est, et omnes sciunt iura civium servanda esse.

Why is lex followed by clara est?

Because clara is an adjective describing lex, and est is the verb is.

So Lex clara est literally means The law is clear.

Notice that clara is feminine singular nominative because it agrees with lex, which is a feminine singular noun.

Why is clara feminine?

Because Latin adjectives must agree with the noun they describe in:

Here:

So the adjective must also be feminine singular nominative: clara.

A learner coming from English often expects adjectives not to change, but in Latin they do.

What does omnes mean here, and why is there no noun with it?

Omnes means all or everyone here.