חומרי הגמר הגיעו היום.

Because חומרי is the construct form of חומרים.

• חומרים = materials
• חומרי = materials of ...

Hebrew often links two nouns this way. This structure is called the construct state or סמיכות. So:

• חומרי הגמר = finishing materials / the materials of the finish

In a construct phrase, the first noun normally does not take ה־. The definiteness is usually shown on the second noun.

So:

• חומרי הגמר = the finishing materials
• חומרי גמר = finishing materials, more indefinite or general

Even though חומרי has no ה־, the whole phrase can still be definite because הגמר is definite.

It is a two-noun phrase:

• חומרי = materials of ...
• הגמר = the finish / the completion

Literally, it is something like materials of the finishing. In natural English, that becomes finishing materials or the finishing materials.

This is a very common Hebrew pattern.

Literally, גמר means completion, end, or finish. In practical contexts such as construction, renovation, or design, גמר often refers to the finishing stage.

So חומרי הגמר usually means materials used in the finishing stage, such as paint, tiles, trim, and similar items.

Because the subject, חומרי הגמר, is plural.

• singular: הגיע = arrived
• plural: הגיעו = arrived

Hebrew verbs in the past tense agree with the subject in number, so a plural subject needs a plural verb.

In this form, הגיעו is simply third person plural past. In modern Hebrew, this same form is used for both masculine and feminine plural subjects.

So here it matches חומרי הגמר, which is a plural noun phrase.

Because חומרי הגמר is the subject, not a direct object.

את is used before a definite direct object. But הגיעו means arrived, and arrive does not take a direct object here.

So:

• חומרי הגמר הגיעו היום = the finishing materials arrived today

No את is needed.

Yes. Hebrew word order is flexible.

This sentence:

• חומרי הגמר הגיעו היום

is a very natural, straightforward way to say it.

But you could also say:

• היום הגיעו חומרי הגמר = emphasizes today
• הגיעו היום חומרי הגמר = also possible, depending on style and emphasis

The basic meaning stays the same, but the focus can shift a little.

A simple pronunciation guide is:

chomrei ha-gmar higi'u hayom

A few notes:

• ח in חומרי is a throaty sound, not an English h
• חומרי sounds roughly like khom-REI
• הגיעו has a slight break before the last vowel: hi-gi-U
• היום = ha-YOM

Very often, yes. In this sentence, it clearly means today.

The same word can also mean the day in some contexts, but here with a verb like arrived, the natural reading is definitely today.

Sometimes, yes, depending on context. Hebrew past tense often covers what English expresses as either:

• arrived
• have arrived

In this specific sentence, arrived today is usually the most natural English translation.