Learn Hardcore Russian: Это факт.

Это here is a demonstrative pronoun (often called a “dummy subject”) that introduces or identifies something. In English it corresponds to “this is,” “that is,” or simply “it is.” Russian does not use a linking verb in the present tense, so Это + noun is how you say “This is a [noun].”

Why isn’t there any verb like “to be” in Это факт?

In modern Russian the verb быть (“to be”) is normally omitted in the present tense. You would use a form of быть in the past or future (e.g. Это было фактом, Это будет фактом), but for present statements you simply say Это + noun (or adjective).

Why is факт in the nominative case?

After Это the noun remains in the nominative because it is a predicate nominative (a noun complement linked to the subject). In other words, Это and факт form a simple “X is Y” construction without an explicit verb, so both parts stay nominative.

What’s the difference between Это and Этот?

Это is an invariable pronoun used to introduce or point to something: “This is/That is.”
Этот is a demonstrative adjective that must match gender, number, and case of a noun (e.g. этот факт, эта идея, эти факты).
You cannot say Этот факт on its own the same way as Это факт; you would need a verb or further context (e.g. Этот факт известен всем – “This fact is known to everyone”).

Why don’t we need an article before факт, like “a fact” or “the fact”?

Russian has no articles. Definiteness or indefiniteness is understood from context or added words (e.g. этот факт “this fact,” любой факт “any fact”). Here Это conveys that specific “fact” is being pointed out, so no separate word for “the” or “a” is needed.

How do you pronounce Это факт, and where are the stresses?

You pronounce it as [ˈɛ.tə ˈfakt].

Э́то – stress on the first syllable: É-to
Фа́кт – stress on the only vowel: FÁKT

Can I just say Факт instead of Это факт?

Saying Факт! on its own can work as a colloquial exclamation, roughly “Fact!” or “Exactly!” However, if you want the full meaning “That’s a fact,” you need Это факт. Dropping Это may sound abrupt or slangy.

Why can’t I say Он факт to mean “it’s a fact”?

Он is a personal pronoun (“he/it” referring to a specific masculine noun already mentioned). In Russian, you don’t use он as a dummy subject to introduce a new idea. Instead, Это is the fixed form for “this/that is” when presenting or naming something.