Η εξέταση της ένστασης ελέγχει την πράξη βεβαίωσης παράβασης.

The subject is Η εξέταση της ένστασης.

The head noun is εξέταση and it is in the nominative singular, so that is what the verb agrees with.
The part της ένστασης is attached to it and means of the objection / appeal, but it is not the grammatical subject by itself.

So the structure is:

• Η εξέταση της ένστασης = the review/examination of the objection
• ελέγχει = checks/reviews
• την πράξη βεβαίωσης παράβασης = the act/report of certification of a violation

Because Greek articles change depending on case, gender, and number.

Here they are all feminine singular, but in different cases:

• η = nominative feminine singular
  used for the subject
  → η εξέταση

• της = genitive feminine singular
  often used for of
  → της ένστασης

• την = accusative feminine singular
  used for the direct object
  → την πράξη

So English uses one word, the, but Greek changes the form.

Because after εξέταση, Greek uses the genitive to show the relationship of the objection.

The dictionary form is:

• η ένσταση = the objection

But in this sentence it becomes:

• της ένστασης = of the objection

This is very common in Greek. A noun followed by another noun in the genitive often works like English of + noun.

So:

• η εξέταση της ένστασης = the examination/review of the objection

Because the subject is singular: η εξέταση.

Even though there are several nouns in the sentence, the verb agrees with the main subject, not with every noun around it.

So:

• η εξέταση = singular
• therefore ελέγχει = he/she/it checks, 3rd person singular

The phrase της ένστασης does not change the number of the verb, because it is just a genitive modifier.

Την πράξη is the direct object, so it is in the accusative.

The dictionary form is:

• η πράξη = the act

In the accusative singular, many feminine nouns in -η / -ξη keep the same noun form:

• nominative: η πράξη
• accusative: την πράξη

So the noun πράξη itself looks the same, but the article changes and shows the case.

This is a chain of genitives.

The dictionary forms are:

• η βεβαίωση = certification, confirmation, recording
• η παράβαση = violation, infringement

In the sentence they appear as:

• βεβαίωσης = of certification / of recording
• παράβασης = of violation

Together they modify πράξη:

• την πράξη βεβαίωσης παράβασης

Literally, this is something like:

• the act/report of certification of violation

This kind of stacked genitive structure is very common in formal, legal, and administrative Greek.

Because Greek often omits the article in formal noun strings like this, especially in administrative or legal language.

So instead of something heavier like:

• την πράξη της βεβαίωσης της παράβασης

you often get the more compact official style:

• την πράξη βεβαίωσης παράβασης

This sounds more like a fixed term or document title.
In everyday Greek, people might sometimes rephrase it to make it clearer, but this article-less genitive style is very normal in formal writing.

They are:

• η εξέταση → in the sentence: Η εξέταση
• η ένσταση → in the sentence: της ένστασης
• η πράξη → in the sentence: την πράξη
• η βεβαίωση → in the sentence: βεβαίωσης
• η παράβαση → in the sentence: παράβασης

A very useful habit in Greek is to identify the dictionary form first, then notice how case changes the form in the sentence.

Greek word order is more flexible than English because case endings and articles help show each word’s role.

The sentence here uses a straightforward order:

• subject + verb + object

So:

• Η εξέταση της ένστασης = subject
• ελέγχει = verb
• την πράξη βεβαίωσης παράβασης = object

But Greek could move things around for emphasis, for example:

• Την πράξη βεβαίωσης παράβασης ελέγχει η εξέταση της ένστασης

That sounds more marked or formal, but it is still understandable because the cases show what each part is doing.

Not necessarily. Ελέγχω can mean several related things depending on context, such as:

• check
• inspect
• review
• verify
• audit
• examine

In official or legal Greek, it often has a more formal sense than simple everyday check. So learners should be careful not to connect it only with one English verb.

Also, it does not always mean control in the English sense, even though that can sometimes appear in translations.

Yes. It sounds formal, administrative, or legal.

Clues include:

• the abstract noun εξέταση
• the official noun ένσταση
• the compact genitive chain πράξη βεβαίωσης παράβασης

In everyday speech, a speaker might use a less dense structure. But in official documents, this style is very common and worth getting used to.