ابحث عن المحفظة؛ وصفها ومكان الفقدان مهمان.

ابحث is an imperative verb: search / look for.

More specifically, it is:

• 2nd person
• masculine singular
• from the verb بَحَثَ = to search / to look for

So it is addressing one male directly, or sometimes a general reader/listener in instructional language.

A common pronunciation is ibḥath.

Related forms:

• to one female: ابحثي
• to a group: ابحثوا

Because in Arabic, the verb بحث in the sense of to search for / look for normally takes the preposition عن.

So:

• بحث عن شيء = to search for something

That means:

• ابحث عن المحفظة = Look for the wallet

This is similar to how English says look for rather than just look.

A useful nuance:

• بحث عن = searched for
• بحث في = researched / examined / discussed a topic

So the preposition matters.

In present-tense Arabic, the verb to be is usually not written in sentences like this.

So Arabic often says literally:

• its description and place of loss important

but the natural English meaning is:

• Its description and the place of loss are important

This is called a nominal sentence.

If you wanted past tense, Arabic would use a form of كان:

• وصفها ومكان الفقدان كانا مهمين = Its description and the place of loss were important

المحفظة is a grammatically feminine noun. One clear clue is the ending ـة.

Because it is feminine, the attached pronoun referring back to it is ها.

So:

• وصفها = its description

Even though ها can mean her or its, here it means its, because it refers to المحفظة.

Arabic distinguishes gender, not the English difference between her and its.

Here, وصفها is a noun phrase, not a verb.

It is made of:

• وصف = description
• ها = its / her

So it means:

• its description

Why not a verb here? Because the sentence structure shows that وصفها is one of the two things being talked about:

• وصفها and مكان الفقدان are the two subjects
• مهمان is the predicate describing them

You are right that the same spelling وصفها could also, in another context, be read as a verb:

• وصفها = he described her/it

But in this sentence, the meaning and grammar clearly make it waṣfuhā = its description.

مكان الفقدان is an iḍāfa construction, often called a genitive/construct phrase.

It consists of:

• مكان = place
• الفقدان = the loss / losing

So literally it means:

• the place of the loss

In natural English, that often becomes:

• the place where it was lost
• the place of loss

A key iḍāfa rule:

• the first noun usually does not take ال
• the second noun can be definite, and that makes the whole phrase definite

So:

• مكان الفقدان = the place of loss

Both are possible in good Arabic, but they are slightly different in style.

• مكان الفقدان = the place of loss
• مكان فقدانها = the place of its loss / the place where it was lost

The version in your sentence is a bit more formal and general-sounding, which fits Modern Standard Arabic well.

MSA often prefers abstract nouns such as:

• الفقدان = loss
• الضياع = losing / being lost

So this sentence has a fairly formal written style.

Because it describes two things:

• وصفها
• مكان الفقدان

When Arabic has two coordinated items like this, the predicate can appear in the dual.

So:

• one important thing: مهم
• two important things: مهمان
• more than two: مهمون / مهمة depending on the context

Here the sentence is essentially:

• Its description and the place of loss are both important

That is why مهمان is used.

Because مهمان is the nominative dual form.

Dual endings in Arabic are:

• ـانِ / ـان in the nominative
• ـينِ / ـين in the accusative and genitive

In this sentence, مهمان is the predicate of a nominal sentence, so it is in the nominative.

So:

• مهمان = correct here

You would see مهمين in a different grammatical role, such as after a preposition or as an object.

A practical pause-style pronunciation is:

ibḥath ʿan al-maḥfaẓa; waṣfuhā wa makān al-fuqdān muhimmān.

If you want a more fully inflected reading, it would be approximately:

اِبْحَثْ عَنِ الْمَحْفَظَةِ؛ وَصْفُهَا وَمَكَانُ الْفُقْدَانِ مُهِمَّانِ

A few notes:

• ابحث = ibḥath
• المحفظة = al-maḥfaẓa
• وصفها = waṣfuhā
• مهمان = muhimmān

؛ is the Arabic semicolon.

It is used to connect two closely related clauses, often when the second clause:

• explains the first
• gives a reason
• adds an important consequence

That fits this sentence well:

• Look for the wallet;
• its description and the place of loss are important.

So the second part helps explain why the search matters or what information is useful.