Registrul comerțului arată sediul social.

Because -ul is the Romanian definite article attached to the end of a masculine/neuter singular noun.

• registru = a register
• registrul = the register

Romanian usually puts the definite article at the end of the noun, unlike English, which uses a separate word such as the.

This is the genitive/dative definite singular form of comerț.

Here it shows possession or relationship:

• comerț = commerce / trade
• comerțului = of the commerce / of trade

So Registrul comerțului literally works like the register of trade/commerce.

The ending -ului is very common for masculine and neuter nouns in the singular when they are definite and in the genitive/dative.

Because Romanian often uses the genitive case instead of a separate preposition.

English says:

• the register of commerce

Romanian often says the equivalent by changing the noun form:

• registrul comerțului

So instead of adding a separate of, Romanian marks that relationship with the ending on comerțului.

Because in Romanian, when a noun has a following adjective, the definite article normally goes on the noun, not on the adjective.

• sediu social = a registered office
• sediul social = the registered office

Here:

• sediul = the office/headquarters
• social = adjective meaning registered / corporate in this legal expression

This is normal Romanian word order: noun + adjective.

Not really in the everyday sense of sociable or related to society.

In the legal/business expression sediu social, it means something like:

• registered office
• official company address
• legal headquarters

So this is a fixed legal phrase, and it should be understood as a technical term rather than translated word-for-word.

arată is the 3rd person singular present tense of a arăta.

So it matches the singular subject Registrul comerțului.

• eu arăt = I show
• tu arăți = you show
• el/ea arată = he/she/it shows

In this sentence, the subject is singular, so arată is the correct form.

Yes. In administrative or formal contexts, a arăta can also mean:

• to indicate
• to state
• to list
• to display

So in this kind of sentence, it may sound more natural in English as shows, indicates, or lists, depending on context.

It is the direct object of the verb arată, so it is in the accusative.

In Romanian, for many nouns, the nominative and accusative forms look the same, so you do not see a special ending here.

Structure of the sentence:

• Registrul comerțului = subject
• arată = verb
• sediul social = direct object

This is the most natural neutral word order:

• subject + verb + object

So:

• Registrul comerțului arată sediul social.

Romanian word order is somewhat flexible, but changing it usually changes emphasis or makes the sentence sound more marked.

For example, you could move things around in special contexts, but this version is the standard, straightforward one.

Two important Romanian sounds appear here:

• ț sounds like ts in cats
• ă is a short central vowel, somewhat like the a in sofa, but shorter and more neutral

So:

• comerțului contains ț = ts
• arată ends in ă
• sediul also contains an i/u sequence that learners often need to listen to carefully

A rough pronunciation guide:

• Registrul ≈ reh-JEES-trool
• comerțului ≈ ko-MERTS-oo-luy
• arată ≈ a-RA-tuh
• sediul social ≈ SEH-dee-ool so-see-AL

These are only approximations, but they help with the main sounds.

It depends on whether you mean the phrase generically or as an official institution name.

• In a general sense, lowercase is normal: registrul comerțului
• If it is part of an official name, capitalization may be used: Registrul Comerțului

In real Romanian usage, official names often have more capitalization, but ordinary sentence style may keep things lowercase unless it is clearly treated as a proper name.

Yes, Romanian can sometimes express these relationships in more than one way.

You may see patterns like:

• registrul comerțului
• registru al comerțului

But they are not always interchangeable in every context.

In your sentence, Registrul comerțului is a very natural and established way to say the trade register / register of commerce. It sounds like a standard official or institutional phrase.