Технический надзор проверяет скрытые работы.

Yes, технический надзор is the subject of the sentence.

Literally, it means technical supervision or technical oversight:

• технический = technical
• надзор = supervision, oversight, inspection

In construction and engineering contexts, технический надзор is a standard term for the body, specialist, or function responsible for checking that work is done correctly.

Even though English might prefer something like the technical inspector or construction supervision, Russian often uses this abstract noun phrase as the subject.

Because the grammatical subject is singular: надзор is a singular masculine noun.

So:

• надзор проверяет = supervision checks / the inspectorate checks

Even though the phrase has two words, only надзор is the main noun. Технический is just an adjective describing it.

That is why the verb is singular:

• проверяет = he/she/it checks

Скрытые работы is in the accusative plural, because it is the direct object of проверяет.

The verb проверять / проверить takes a direct object:

• проверять что? = to check what?

So we get:

• проверяет скрытые работы = checks hidden works

Why does it look the same as the nominative plural?

Because работы is an inanimate plural noun. In Russian, for inanimate plural nouns, the accusative plural is the same as the nominative plural.

So:

• nominative: скрытые работы
• accusative: скрытые работы

No visible change happens here.

Because the sentence is talking about multiple items of work, not one single task.

• скрытую работу = one hidden work item / one concealed operation
• скрытые работы = hidden works / concealed works / work that will later be covered up

In construction Russian, работы is very often used in the plural to mean types of work, stages of work, or operations.

So скрытые работы is a standard technical expression, not just a literal everyday phrase.

No, it does not mean secret work in the everyday sense.

In construction, скрытые работы means work that will later be covered up and become impossible or difficult to inspect visually. For example:

• reinforcement before concrete is poured
• waterproofing under later layers
• wiring inside walls
• pipework before closing structures

So a more natural English equivalent is often:

• concealed works
• hidden works
• work that will later be covered over

This is a technical term.

Проверяет is the imperfective present form of проверять.

It is used here because the sentence describes:

• a general function
• a routine responsibility
• a repeated action

So the meaning is something like:

• Technical supervision checks concealed works
• Technical supervision is responsible for checking concealed works

If you used проверит instead, that would be perfective future:

• Технический надзор проверит скрытые работы.
• Technical supervision will check the concealed works.

So:

• проверяет = checks / is checking / does check
• проверит = will check

In Russian, the present tense of an imperfective verb can often translate into English in more than one way:

• checks
• is checking
• sometimes even does check

The exact English version depends on context.

In this sentence, with no extra context, the most natural reading is usually a general statement:

• Technical supervision checks concealed works

But in the right context, it could also mean:

• Technical supervision is checking the concealed works

Russian does not always mark this distinction as explicitly as English does.

The dictionary forms are:

• технический = technical
• надзор = supervision / oversight
• проверять = to check, to inspect
• скрытый = hidden, concealed
• работа = work, job, task

The sentence uses these forms:

• технический → masculine singular nominative, matching надзор
• проверять → проверяет, 3rd person singular present
• скрытый → скрытые, plural accusative (same form as nominative plural here)
• работа → работы, plural accusative (same form as nominative plural here)

Yes. Russian word order is more flexible than English.

The neutral order here is:

• Технический надзор проверяет скрытые работы.

But you could also say:

• Скрытые работы проверяет технический надзор.

That version puts more focus on скрытые работы.

Even so, the original sentence is the most neutral and standard:

• subject → verb → object

Russian uses endings and context more than English to show grammatical roles, so changing the order often changes emphasis, not the core meaning.

Russian has no articles, so there is no word corresponding directly to the or a/an.

That means:

• Технический надзор проверяет скрытые работы could mean
  • Technical supervision checks concealed works
  • The technical supervisor checks the concealed works
  • Technical oversight checks hidden work items

The exact choice in English depends on context.

Russian leaves definiteness unstated unless something else makes it clear.

The stress is:

• техни́ческий
• надзо́р
• проверя́ет
• скры́тые
• рабо́ты

A helpful pronunciation guide:

• техни́ческий ≈ tekh-NEE-chee-skiy
• надзо́р ≈ nad-ZOR
• проверя́ет ≈ pra-vye-RYA-yet
• скры́тые ≈ SKRY-ty-ye
• рабо́ты ≈ ra-BO-ty

Stress is important in Russian, because it is not always predictable and can affect pronunciation strongly.