هو يقلق بشأن العمل.

Because Arabic verbs already show the subject. So يقلق by itself can mean he worries / he is worried.

Adding هو can:

• make the subject extra clear,
• add slight emphasis,
• or give the sentence a more topic-first feel: As for him, he worries about work.

So هو is not strictly necessary, but it is completely natural.

Yes. يقلق بشأن العمل is a natural sentence in MSA and already means He worries about work.

There is a small difference in feel:

• هو يقلق بشأن العمل = subject-first, slightly more explicit or emphatic
• يقلق بشأن العمل = more neutral, verb-first

Both are correct.

يقلق is in the imperfect tense, which often covers:

• the present: he worries
• an ongoing situation: he is worrying / he is worried
• sometimes near future, depending on context

In this sentence, the most natural meaning is present: he worries about work or he is worried about work.

In context, it expresses a state of anxiety or concern, so English may translate it either way:

• He worries about work
• He is worried about work

Both are reasonable.

If you want a more adjective-like Arabic sentence, you could also say: هو قَلِقٌ بشأن العمل which is closer to He is worried about work.

بشأن means regarding, concerning, or about.

It is a fairly formal MSA expression. You will often see it in:

• news writing
• formal speech
• essays
• official language

So بشأن العمل means about work or concerning work.

Because Arabic does not always match English prepositions one-for-one.

In this sentence, بشأن is a very natural MSA choice for about/concerning. It sounds formal and standard.

عن can also mean about in many contexts, but you should not assume it works the same way with every verb. It is best to learn يقلق بشأن as a common MSA combination meaning to worry about / be concerned about.

Arabic often uses the definite article ال where English uses a bare noun.

So العمل can mean:

• work in a general sense
• the work
• sometimes the job

The exact meaning depends on context. Here, English would usually just say work, even though Arabic uses العمل.

Because بشأن is historically made from:

• بـ = with / regarding
• شأن = matter, affair

So بشأن العمل is literally something like with regard to the matter of work.

Grammatically:

• شأن is governed by بـ
• العمل is attached to شأن in an iḍāfa construction, so it is also genitive

In full case-marked form, it would be: بِشَأْنِ العَمَلِ

A careful MSA pronunciation is:

huwa yaqlaqu bi-sha'ni al-ʿamali

A rough guide:

• هو = huwa
• يقلق = yaqlaqu
• بشأن = bi-sha'ni
• العمل = al-ʿamali

The ʿ in ʿamali represents the Arabic letter ع, which has no exact English equivalent.

Yes. Since normal Arabic spelling usually leaves out short vowels, يقلق can be ambiguous by itself.

In this sentence, with the meaning given, it is understood as the verb meaning he worries / he is worried.

But the same consonants can also represent a different vocalization, يُقْلِقُ, which means he worries/disturbs [someone or something]. That other reading usually needs an object, so context helps you know which meaning is intended.