المستأجر يجدد عقد الإيجار.

A careful full reading is:

al-mustaʔjiru yujaddidu ʿaqda al-ījāri

In normal pause, many speakers say something closer to:

al-mustaʔjir yujaddid ʿaqd al-ījār

A few pronunciation notes:

• ʔ represents the hamza, a brief catch in the throat.
• ʿ represents ع, which has no exact English equivalent.
• ī in الإيجار is a long vowel.
• The l of ال is pronounced clearly here.

المستأجر means the tenant or the lessee.

It comes from the verb استأجر, which is related to renting or hiring. So مستأجر is literally the person who rents something.

Because عقد الإيجار is an iḍāfa construction, often called a possessive or annexation structure.

So:

• عقد = contract
• الإيجار = the rent / the leasing

Together, عقد الإيجار means the lease contract or the rental contract.

In an iḍāfa:

• the first noun usually does not take ال
• the second noun can take ال
• the whole phrase can still be definite

So even without ال, عقد is definite here because it is tied to الإيجار.

Because both م in المستأجر and the initial hamza in الإيجار belong to the moon-letter group.

That means the ال is pronounced as al-, not assimilated.

So you say:

• al-mustaʔjir
• al-ījār

If the next letter were a sun letter, the l sound would disappear in pronunciation.

يجدد is in the imperfect form.

In this sentence, it usually means a present-time action such as:

• renews
• is renewing

Depending on context, the imperfect can also refer to the future, but by itself here it is most naturally read as present.

Because the verb is Form II: جَدَّدَ.

That doubled middle consonant is shown by a shadda:

• جَدَّدَ = he renewed
• يُجَدِّدُ = he renews / is renewing

Form II often gives a causative, intensive, or repeated sense. Here it gives the idea of renewing something, literally making it new again.

Because the verb يجدد already includes the meaning he renews.

Arabic verbs normally show:

• person
• number
• gender

So يجدد already tells you the subject is he. Since the sentence also explicitly gives the subject as المستأجر, there is no need for هو.

If هو were added, it would usually be for emphasis or contrast.

Arabic allows both word orders:

• المستأجر يجدد عقد الإيجار
• يجدد المستأجر عقد الإيجار

Both are correct.

The version starting with المستأجر is a common subject-first pattern and can feel a little more like As for the tenant, he renews the lease.

The verb-first version is also very normal in Arabic. The choice often depends on style, emphasis, and context.

If fully vowelled, the sentence is:

المُسْتَأْجِرُ يُجَدِّدُ عَقْدَ الإِيجَارِ

Here is why:

• المستأجرُ ends in -u because it is the subject, so it is nominative
• يجددُ ends in -u because it is in the indicative
• عقدَ ends in -a because it is the direct object, so it is accusative
• الإيجارِ ends in -i because it is the second term of an iḍāfa, so it is genitive

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

Often yes, but its exact English translation depends on context.

الإيجار can refer to:

• renting
• leasing
• rent
• a lease arrangement

In عقد الإيجار, it is best understood as lease or rental, so the whole phrase means lease contract or rental agreement.

The verb would change to match the subject.

Examples:

• المستأجرة تجدد عقد الإيجار
  The female tenant renews the lease

• المستأجرون يجددون عقد الإيجار
  The tenants renew the lease

So the verb agrees with the subject in gender and number.