العميل هنا اليوم.

In Modern Standard Arabic, present-tense sentences like this often do not use a word for is / am / are.

So Arabic says:

• العميل هنا اليوم
• literally: the client here today

But the meaning is understood as The client is here today.

This is called a nominal sentence. In the present tense, the linking verb is usually omitted.

If you wanted a past or future meaning, Arabic would normally use a verb such as:

• كان العميل هنا اليوم = The client was here today
• سيكون العميل هنا اليوم = The client will be here today

العميل most commonly means:

• the client
• the customer

Which one is best depends on context.

In some contexts, عميل can also mean agent, but in ordinary business or service contexts, client/customer is the most likely meaning.

Also note:

• عميل = a client / customer
• العميل = the client / customer

The الـ at the beginning is the Arabic definite article, like the in English.

Here is the basic breakdown:

• العميل = the subject/topic of the sentence
• هنا = here
• اليوم = today

A more grammar-based explanation:

• العميل is the مبتدأ (the thing being talked about)
• هنا functions as the خبر here, giving the main information about the subject
• اليوم adds time information

So the structure is basically:

• The client
  • here
    • today

Arabic often builds sentences this way without needing a present-tense is.

This is a very common question.

In Arabic, اليوم is simply the normal word for today. Even though it contains الـ, you usually translate it just as today, not the today.

So:

• اليوم = today
• not usually the day in this sentence

Arabic has some time expressions that are fixed this way. So it is best to learn اليوم as a whole word meaning today in many contexts.

A helpful pronunciation guide is:

al-ʿa-mīl hunā al-yawm

Things to notice:

• ع in العميل is the letter ʿayn, a sound English does not really have
• مِي in عميل has a long ee sound
• هنا is pronounced hu-nā, with a long ā at the end
• اليوم is al-yawm

A slightly more careful grammatical pronunciation would be:

al-ʿamīlu hunā al-yawma

But in normal pause at the end of a sentence, the final short vowel is often not pronounced, so learners often hear something closer to:

al-ʿamīl hunā al-yawm

Yes, Arabic word order is somewhat flexible.

العميل هنا اليوم is a natural, neutral way to say it.

You may also see or hear:

• العميل اليوم هنا
  This can put a little more focus on today

Arabic often changes word order for emphasis, style, or focus, not because the basic meaning completely changes.

For a learner, العميل هنا اليوم is a very good standard pattern to use.

No, not in this sentence.

Both هنا and اليوم can function directly as adverbial expressions:

• هنا = here
• اليوم = today

So Arabic can simply say:

• العميل هنا اليوم

You do not need to add في before them here.

That is similar to English, where we also say:

• The client is here today

not:

• The client is in here in today

Yes, in full formal grammar there are case endings, even though they are usually not written in everyday Arabic text.

A fully vowelled version would be:

العَمِيلُ هنا اليَومَ

Why?

• العَمِيلُ ends in ـُ because it is the subject of the nominal sentence
• هنا is an indeclinable adverb, so it does not change in the usual way
• اليَومَ ends in ـَ because it is functioning as an adverb of time

However, in normal unvowelled writing, you will usually just see:

العميل هنا اليوم

And in normal pause, many final short vowels are not pronounced anyway.

Yes. العميل is masculine singular.

If you wanted a feminine singular form, you would say:

• العميلة هنا اليوم = The female client/customer is here today

If you wanted the plural:

• العملاء هنا اليوم = The clients/customers are here today

The sentence pattern stays the same. Arabic still does not need a present-tense are in this kind of sentence.

Yes. It is simple, clear, and natural in MSA.

It works well as a basic example of:

• a present-tense nominal sentence
• no written is
• a definite subject
• place and time expressions together

In real everyday conversation, many native speakers would use their local dialect instead of MSA, but as a Modern Standard Arabic sentence, العميل هنا اليوم is perfectly good.