Războiul ucide oameni.

Because Romanian usually puts the definite article at the end of the noun.

• război = war
• războiul = the war

The ending -ul is the definite article here. So războiul is the definite form of război.

In Romanian, the definite form is often used in general statements or generic truths, where English often uses no article.

So:

• Războiul ucide oameni = War kills people

Even though războiul literally looks like the war, the sentence is understood as a general statement. Context decides whether it means a general truth or a specific war.

ucide is the 3rd person singular present tense of a ucide, meaning to kill.

It matches the subject războiul, which is singular.

So:

• eu ucid = I kill
• el/ea ucide = he/she/it kills

Here, războiul ucide literally means the war kills or, more naturally in English, war kills.

Romanian does not have a separate continuous form like English is killing. The present tense can cover several meanings depending on context.

So ucide can mean:

• kills
• is killing

In this sentence, though, it most naturally sounds like a general truth: War kills people.

Because oameni means people in a general, indefinite sense, while oamenii means the people.

• oameni = people
• oamenii = the people

In this sentence, the meaning is general, so Romanian uses oameni.

Yes.

• om = person / man / human being
• oameni = people

This is an irregular plural, so you cannot predict it just by adding a normal ending. It is something you simply learn as a pair:

• om → oameni

Also, oameni usually means people, not specifically male people.

Because pe is often used before a specific or definite human direct object, especially with people.

Here, oameni is indefinite and general, so pe is normally not used.

Compare:

• Războiul ucide oameni = War kills people
• Războiul ucide pe soldații aceia = The war kills those soldiers

So the absence of pe helps show that oameni is a general, nonspecific object.

The sentence uses the basic Romanian word order:

• Subject + Verb + Object

So:

• Războiul = subject
• ucide = verb
• oameni = object

This is the most neutral, straightforward order. Romanian word order can be more flexible than English, but this version is the standard, unmarked one.

A few useful pronunciation notes:

• ă in războiul is like the a in about
• ci in ucide sounds like chee
• oa in oameni is roughly like wa

A rough English-friendly pronunciation is:

• războiul ≈ ruhz-BOY-ul
• ucide ≈ oo-CHEE-deh
• oameni ≈ WAH-men

The main stresses are:

• răzBOIul
• uCIde
• OAmeni

război is a neuter noun.

In Romanian, neuter nouns behave:

• like masculine in the singular
• like feminine in the plural

That matters because the singular definite article is the masculine-style -ul, which gives:

• război → războiul

Its plural is:

• războaie = wars
• războaiele = the wars

In this sentence:

• războiul is in the nominative, because it is the subject
• oameni is in the accusative, because it is the direct object

Romanian does not always show big case changes on the noun itself, especially in simple sentences like this one. Often, case is understood from:

• word function
• articles
• pronouns
• markers like pe

So even if the forms do not look very different, the roles are still clear.