كلمة المرور جديدة.

Because Arabic often leaves out the present-tense to be in simple statements.

So كلمة المرور جديدة literally looks like:

• كلمة المرور = the password
• جديدة = new

But the full meaning is The password is new.

This is called a nominal sentence in Arabic.

A verb like is would only appear in other tenses, for example:

• كانت كلمة المرور جديدة = The password was new

Because كلمة is a feminine singular noun, and adjectives or predicate adjectives must agree with it.

• كلمة ends in ة and is feminine
• so the matching form is جديدة = new, feminine singular
• جديد would be masculine singular

So:

• كتاب جديد = a new book
• كلمة جديدة = a new word

In your sentence, the subject is كلمة المرور, and its head noun is كلمة, so the predicate must be feminine singular: جديدة.

Here it is the predicate, not an attributive adjective inside the noun phrase.

So:

• كلمة المرور جديدة = The password is new

But compare:

• كلمة المرور الجديدة = the new password

That difference is very important.

A useful rule:

• definite noun + indefinite adjective/predicate often gives a full sentence: The password is new
• definite noun + definite adjective gives one noun phrase: the new password

So جديدة has no الـ here because it is the predicate.

Because this is an iḍāfa construction, often called a genitive/construct phrase.

كلمة المرور literally means something like:

• word of access/passage

and idiomatically it means password.

In an iḍāfa:

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

So:

• كلمة مرور = a password
• كلمة المرور = the password

That is why كلمة does not have الـ here.

In an iḍāfa, definiteness is usually marked on the last noun, and that makes the whole phrase definite.

So in:

• كلمة المرور

the second word المرور has الـ, and that makes the whole expression definite: the password.

This is different from English, where we usually expect the equivalent of the at the beginning.

Arabic structure here is:

• first noun: كلمة
• second noun: المرور
• together: كلمة المرور = the password

It is an iḍāfa phrase, a very common Arabic structure.

Basic pattern:

• noun + noun
• often translated as X of Y or as a compound noun

Examples:

• باب البيت = the door of the house / the house door
• مدير المدرسة = the director of the school / the school principal
• كلمة المرور = the password

In this structure:

1. the first noun is the main noun
2. the second noun specifies it
3. the first noun does not take الـ
4. the second noun is in the genitive when fully vocalized

So كلمة المرور behaves as one unit meaning password.

It would be:

كَلِمَةُ الْمُرُورِ جَدِيدَةٌ

Here is what the endings show:

• كَلِمَةُ = nominative, because it is the subject
• الْمُرُورِ = genitive, because it is the second term of the iḍāfa
• جَدِيدَةٌ = nominative, because it is the predicate

In normal writing, these short vowels are usually omitted, so you just see:

كلمة المرور جديدة

The ة is called tāʾ marbūṭa.

Its pronunciation depends on position:

• At the end of a pause, it usually sounds like -a
• When followed grammatically by something, it can sound like -t

So in this sentence:

• كلمة in كلمة المرور is part of an iḍāfa, so the ة is pronounced as t
• جديدة at the end of the sentence is usually pronounced with final -a in normal pause

A natural pronunciation without full case endings is:

kalimat al-murūr jadīda

If someone reads very carefully with full case endings, it could be:

kalimatu al-murūri jadīdatun

You would say:

كلمة المرور الجديدة

This is different from:

• كلمة المرور جديدة = The password is new
• كلمة المرور الجديدة = the new password

Why?

Because when an adjective directly modifies a definite noun phrase, the adjective must also be definite:

• كلمة المرور = the password
• الجديدة = the new

So adding الـ to جديدة changes it from a predicate into an attributive adjective inside the noun phrase.