Nevím, co je pravda.

I don't know what is true.

Breakdown of Nevím, co je pravda.

• já: I
• být: to be
• pravda: the truth
• vědět: to know

Questions & Answers about Nevím, co je pravda.

What does Nevím literally mean, and how is it formed?

Nevím means “I don’t know”.

Grammatically:

• The verb is vědět = “to know (a fact)”.
• vím = “I know” (1st person singular, present).
• The negative prefix ne- is added in front of the verb: ne + vím → nevím = “I don’t know”.

So Nevím, co je pravda. is literally “I-don’t-know what is truth.”

Why is there a comma before co?

Czech always separates a subordinate clause from the main clause with a comma.

• Nevím is the main clause: “I don’t know”.
• co je pravda is a subordinate clause (an indirect question): “what is true / what the truth is”.

Therefore you must write: Nevím, co je pravda.
Leaving out the comma is incorrect in standard written Czech.

What exactly does co mean here, and why is it used?