Машинный перевод запрещён.

Because машинный agrees with перевод, and перевод is a masculine singular noun.

In Russian, adjectives must match the noun in gender, number, and case:

• машинный перевод — masculine singular
• машинная ... — feminine singular
• машинное ... — neuter singular
• машинные ... — plural

So here:

• перевод = translation
• машинный перевод = machine translation

They are in the nominative singular.

This sentence is basically saying Machine translation [is] prohibited, so машинный перевод is the thing being described. In Russian, that noun phrase is normally in the nominative in this kind of statement.

So:

• машинный — nominative masculine singular
• перевод — nominative masculine singular

Запрещён means prohibited / forbidden.

Grammatically, it is the short form of запрещённый. In modern Russian, forms like this are very commonly used in statements such as:

• Вход запрещён — Entry is prohibited
• Курение запрещено — Smoking is prohibited
• Машинный перевод запрещён — Machine translation is prohibited

It agrees with перевод, which is masculine singular, so we get:

• masculine: запрещён
• feminine: запрещена
• neuter: запрещено
• plural: запрещены

Because in the present tense, Russian normally omits the verb to be.

So where English says:

• Machine translation is prohibited

Russian simply says:

• Машинный перевод запрещён.

This is completely normal. The idea of is is understood automatically.

Because it agrees with перевод, which is a masculine noun.

Russian often makes the predicate match the noun it describes. Since перевод is masculine singular, the form must also be masculine singular:

• перевод запрещён
• not перевод запрещена
• not перевод запрещено

Compare:

• Книга запрещена — The book is prohibited
• Письмо запрещено — The letter/document is prohibited
• Документы запрещены — The documents are prohibited

For a learner, the most useful way to think about it is: it behaves a lot like a predicate adjective meaning forbidden/prohibited.

Historically and grammatically, it comes from a participial form related to the verb запретить (to forbid / prohibit). But in sentences like this, it is best understood as the normal Russian way to say that something is prohibited.

So you do not need to translate it word-for-word as a full English verb form. Just read the whole sentence naturally as:

• Machine translation is prohibited.

The full form is запрещённый.

So you have:

• запрещённый — full form
• запрещён — short form masculine singular

The short form is very common when saying that something is in a certain state:

• дверь закрыта — the door is closed
• вопрос решён — the issue is resolved
• перевод запрещён — translation is prohibited

The full form is used more like a normal adjective before a noun:

• запрещённый предмет — a prohibited item

Because in Russian writing, ё is often written as е, especially in ordinary printed text.

So:

• запрещён
• запрещен

can represent the same word.

However, the pronunciation and stress are still those of ё. For learners, it is helpful to remember the correct form as запрещён.

The stress is:

• маши́нный перево́д запрещён

More specifically:

• маши́нный — stress on и
• перево́д — stress on о
• запрещён — stress on ё

Stress matters in Russian, so it is worth learning these together with the words.

Yes, very natural.

Машинный перевод запрещён sounds like a rule, notice, or policy statement. It is short, clear, and formal enough for instructions.

A more bureaucratic or official-sounding variant is:

• Машинный перевод запрещается.

Both are correct, but запрещён often feels more like a plain statement of status, while запрещается can sound more like regulation language.

Yes. Машинный перевод is the standard Russian term for machine translation.

It refers to translation done automatically by software or a machine, not by a human translator.

So in context, the sentence means that using machine translation tools is not allowed.

Yes, but the given order is the most neutral and natural here:

• Машинный перевод запрещён.

Russian word order is more flexible than English, but changing it changes emphasis.

For example:

• Запрещён машинный перевод. — possible, but more marked; it can sound like emphasis on prohibited
• Перевод машинный запрещён. — unnatural in normal usage

For a learner, the original sentence is the best model to copy.

Because машинный перевод is the established standard term for machine translation.

You may also see words like автоматический in other contexts, but машинный перевод is the normal fixed phrase used for the concept itself.

So even though English speakers might think of automatic translation, Russian usually names the concept as машинный перевод.