هو يكمل الدورة المسائية.

In Arabic, the verb يكمل already tells you the subject is he. So هو is often optional.

• يكمل الدورة المسائية = He completes / is completing the evening course
• هو يكمل الدورة المسائية = the same basic meaning, but with extra emphasis, contrast, or clarity

A speaker might include هو to stress he in particular, or to make the sentence clearer in context.

يكمل is in the imperfect form. In Modern Standard Arabic, the imperfect can express several English ideas depending on context, such as:

• he completes
• he is completing
• he completes regularly
• sometimes even he will complete if there is a future marker or enough context

So Arabic does not always separate simple present and present continuous the way English does.

In MSA, يكمل here most naturally means completes or finishes.

It comes from the root ك-م-ل, connected with completeness. In this sentence, the idea is that he is bringing the course to completion.

Be careful: in some spoken varieties, forms from this root can sometimes be used more like continue, but in standard Arabic the core meaning is usually complete / finish.

الدورة is a feminine noun. Many Arabic nouns ending in ـة (taa marbuuTa) are feminine, and دورة is one of them.

Because it is feminine, any adjective describing it must also be feminine. That is why the adjective is المسائية, not a masculine form.

Because Arabic adjectives must match the noun they describe in definiteness.

Here:

• الدورة = the course
• المسائية = the evening

Together, الدورة المسائية means the evening course.

If the noun is definite, the adjective must also be definite. You generally cannot say الدورة مسائية if you mean the evening course as a noun phrase.

المسائية means evening in the sense of evening-related or held in the evening.

It is an adjective describing الدورة. So:

• دورة = course
• مسائية = evening / evening-time

So الدورة المسائية is literally the evening course.

This sentence is perfectly correct, but Arabic allows more than one natural word order.

Common possibilities are:

• هو يكمل الدورة المسائية
• يكمل الدورة المسائية

The version without هو is often more natural unless you want emphasis. Arabic frequently leaves the subject pronoun out because the verb already shows it.

So this sentence is correct, but in many contexts you may hear simply:

• يكمل الدورة المسائية

A fully vowelled version would be:

هُوَ يُكْمِلُ الدَّوْرَةَ المَسَائِيَّةَ

A few useful notes:

• هُوَ = he
• يُكْمِلُ = he completes
• الدَّوْرَةَ = direct object, so it takes fatHa in full MSA
• المَسَائِيَّةَ = adjective agreeing with الدورة, also accusative here

In normal unvowelled writing, these endings are usually not written.

Because المسائية is an adjective describing الدورة, and adjectives in Arabic agree with the noun they describe in:

• gender
• number
• definiteness
• case

Here, الدورة is the direct object of the verb, so it is accusative. The adjective must match it, so المسائية is also accusative.

That is why the fully vocalized form is:

• الدَّوْرَةَ المَسَائِيَّةَ

Yes. دورة can have several meanings depending on context, such as:

• course
• session
• cycle
• round

But in a sentence like this, especially in educational contexts, الدورة المسائية is very naturally understood as the evening course.

It is often analyzed as a nominal sentence because it begins with هو, and the predicate is the verbal clause يكمل الدورة المسائية.

But from a learner’s point of view, the most important thing is simpler:

• هو = subject pronoun
• يكمل = verb
• الدورة المسائية = object phrase

Also remember that Arabic often drops the pronoun, giving a more obviously verbal sentence:

• يكمل الدورة المسائية

A basic negation in MSA would be:

هو لا يكمل الدورة المسائية

This means He does not complete / is not completing the evening course, depending on context.

So:

• لا
  • imperfect verb = basic present-tense negation

If you are still early in Arabic study, this is the most useful negated version to remember.