يجب على المستأجر أن يوقع عقد الإيجار.

Yes. يجب means it is necessary, it is obligatory, or in many contexts simply must.

In this sentence, Arabic is using a very common pattern:

يجب على + person + أن + verb

So the structure is roughly:

It is necessary for the tenant to sign the lease contract.

Unlike English, Arabic often expresses must with an impersonal idea like it is necessary.

After يجب, Arabic often uses على to show who the obligation is on.

So:

• يجب على المستأجر = it is obligatory for the tenant
• literally: it is obligatory upon the tenant

This is a very standard pattern in Modern Standard Arabic.

You will also see it with pronouns:

• يجب عليّ = I must
• يجب عليك = you must
• يجب علينا = we must

So in your sentence, على المستأجر tells you that the tenant is the person who has to do the action.

أن is a particle that often introduces a following verb meaning something like to do or that someone do.

Here:

• أن يوقع = to sign

After يجب, Arabic normally uses أن + present tense verb:

• يجب أن... = it is necessary to...
• يجب على المستأجر أن يوقع = the tenant must sign

Grammatically, أن also puts the following present-tense verb into the subjunctive. In fully vocalized Arabic, that would be:

• أن يوقِّعَ

The final -a sound is usually not written in normal text.

Because in this sentence it comes from the verb وقّع meaning to sign.

In normal Arabic writing, short vowels and the shadda are often omitted, so يوقع can look ambiguous. Here the intended reading is:

• يُوَقِّعَ after أن
• or dictionary form: يُوَقِّعُ
• from وقّع

So the pronunciation is approximately:

yuwaqqiʿa here
or yuwaqqiʿu in its basic present form

This is different from other possible readings of the same consonants in unvocalized text. Context tells you which one is meant.

المستأجر means the tenant, the renter, or the lessee.

It comes from the verb استأجر related to renting or hiring. As a noun, مستأجر means the person who rents something.

So:

• المستأجر = the tenant
• المؤجِّر = the landlord / lessor (the one who rents it out)

This is useful because English speakers sometimes confuse the two roles.

Because this is an iḍāfa construction, often called a genitive construction or noun annexation.

عقد الإيجار literally means:

• contract of the renting
• more naturally: the lease contract or rental contract

In an iḍāfa:

1. the first noun usually does not take ال
2. the second noun can make the whole phrase definite if it is definite

So:

• عقد = contract
• الإيجار = the renting / the lease
• عقد الإيجار = the lease contract

You do not say العقد الإيجار in this structure.

That is exactly how iḍāfa works.

In عقد الإيجار:

• the first noun عقد does not take ال
• the second noun الإيجار is definite
• therefore the whole phrase becomes definite

So even though عقد itself does not have ال, the entire expression still means the lease contract, not just a lease contract.

This is very common in Arabic:

• باب البيت = the door of the house / the house door
• مدير المدرسة = the school principal

Because normal Arabic writing usually leaves out short vowels and case endings.

If the sentence were fully vocalized, it would be:

يَجِبُ عَلَى المُسْتَأْجِرِ أَنْ يُوَقِّعَ عَقْدَ الإِيجَارِ

Those endings show the grammar:

• المستأجرِ is genitive after على
• يوقّعَ is subjunctive after أن
• عقدَ is the direct object, so it is accusative
• الإيجارِ is genitive as the second part of the iḍāfa

In everyday printed Arabic, these endings are usually omitted.

Yes, absolutely.

That version is also correct:

• يجب أن يوقع المستأجر عقد الإيجار

It means the same thing: The tenant must sign the lease contract.

The difference is mainly stylistic:

• يجب على المستأجر أن يوقع... emphasizes that the obligation is on the tenant
• يجب أن يوقع المستأجر... is a little more direct and simpler in structure

Both are standard Modern Standard Arabic.

Both patterns are used.

You may see:

• يوقّع عقد الإيجار
• يوقّع على عقد الإيجار

Both can mean sign the lease contract.

In modern usage, وقّع على is very common, especially when talking about signing a document. But using the document directly as the object is also common and correct.

So these are both acceptable:

• يجب على المستأجر أن يوقّع عقد الإيجار
• يجب على المستأجر أن يوقّع على عقد الإيجار

A careful pronunciation is:

yajibu ʿalā al-mustaʾjiri ʾan yuwaqqiʿa ʿaqda al-ʾījāri

A more readable breakdown:

• يجب = yajibu
• على = ʿalā
• المستأجر = al-mustaʾjir
• أن = ʾan
• يوقع = yuwaqqiʿa
• عقد الإيجار = ʿaqda al-ʾījār

A few pronunciation notes:

• ʿ represents the letter ع
• ʾ represents the glottal stop ء
• the doubled consonant in يوقّع is important: qq

So يوقع here is not a simple yuqi... sound; it is yu-waq-qiʿ.