بما ان وثيقة التامين سارية، شركة التامين هتراجع المطالبة التامينية.

It means since / given that / because.

It introduces the reason for the main clause:

• بما ان وثيقة التامين سارية = since the insurance policy is valid
• شركة التامين هتراجع المطالبة التامينية = the insurance company will review the insurance claim

In Egyptian writing, you will often see بما إن. In more formal Standard Arabic, you often see بما أن.

Because Arabic usually leaves out the present-tense verb to be.

So:

• وثيقة التامين سارية literally looks like insurance document valid
• but it means the insurance policy is valid

This is very normal in Arabic. In the past or future, you would use a verb:

• كانت سارية = was valid
• هتكون سارية = will be valid

Because this is an idafa construction, sometimes called a construct phrase.

Structure:

• وثيقة = document
• التأمين = the insurance
• وثيقة التأمين = the insurance document / the insurance policy

In an idafa:

• the first noun normally does not take ال
• the second noun shows the relationship

So Arabic uses noun + noun, where English often uses of or a compound noun.

Because وثيقة is a feminine noun, and the adjective has to agree with it.

So:

• وثيقة ... سارية = feminine noun + feminine adjective
• masculine would be ساري

This adjective means valid, in effect, or active for things like documents, licenses, policies, memberships, etc.

For the same reason: it is also an idafa.

• شركة التأمين = the insurance company

Here:

• شركة = company
• التأمين = the insurance

Because the second part is definite, the whole phrase is definite.

A useful contrast:

• شركة التأمين = the insurance company
• شركة تأمين = an insurance company / an insurance company

Because the subject شركة is grammatically feminine.

In Arabic, verbs agree with the gender of the subject, and شركة is a feminine noun. So the present-tense form is:

• تراجع = she/it reviews

Then Egyptian adds the future marker هـ:

• هتراجع = she/it will review

So even though a company is not female in real life, the noun شركة is grammatically feminine, so the verb follows that grammar.

It is the Egyptian future marker, meaning will.

So:

• تراجع = reviews
• هتراجع = will review

This هـ is very common in Egyptian Arabic.

Compare:

• Egyptian: هتراجع
• More formal Arabic: ستراجع

Here it means will review.

That is because it comes from راجع = to review, examine, check.

This is different from:

• رجع = to return, go back

So:

• هترجع = will return
• هتراجع = will review

That extra long vowel pattern matters.

Because this is noun + adjective, not an idafa.

• المطالبة = the claim
• التأمينية = insurance-related / insurance

In Arabic, adjectives:

• come after the noun
• agree with the noun in definiteness
• agree in gender
• agree in number

So if the noun is definite, the adjective must also be definite:

• المطالبة التأمينية = the insurance claim

They may look similar in English, but they are built differently in Arabic.

1) وثيقة التأمين

• this is idafa: noun + noun
• literally: document of insurance

2) المطالبة التأمينية

• this is noun + adjective
• literally: the claim insurance-related

That is an important distinction, because Arabic expresses relationships in more than one way.

Because casual Arabic writing often leaves hamzas out.

So in careful spelling, you would usually write:

• التأمين
• التأمينية

And for the connector at the beginning:

• in Egyptian-style writing: بما إن
• in more formal Standard Arabic: بما أن

Omitting hamzas is extremely common in texting, chats, and informal online writing.

Not completely. It is a very normal mixed register.

What sounds Egyptian:

• هتراجع for the future

What sounds formal or technical:

• وثيقة
• مطالبة
• تأمينية

This kind of mix is very common in Egyptian Arabic, especially in business, legal, insurance, and official contexts. So the sentence feels natural, even though it is not purely casual everyday speech.