שלחתי את המסמך עבור החברה.

שלחתי means I sent.

It comes from the verb שלח (to send) in the past tense.
The ending ־תי tells you the subject is I.

So:

• שלחתי = I sent
• שלחת = you sent (masculine singular)
• שלחתְ = you sent (feminine singular)
• שלח = he sent
• שלחה = she sent

In Hebrew, the verb itself often tells you who the subject is, so you do not need a separate word for I.

את is the direct object marker. It is used before a definite direct object.

Here, המסמך means the document, which is definite because it has ה־ (the). So Hebrew uses את:

• שלחתי את המסמך = I sent the document

Important: את does not mean with here.
It is just a grammatical marker and is usually not translated into English.

Compare:

• שלחתי מסמך = I sent a document
• שלחתי את המסמך = I sent the document

You use את only with the definite one.

The prefix ה־ is the Hebrew word for the.

So:

• מסמך = document
• המסמך = the document

and

• חברה = company
• החברה = the company

This is how Hebrew usually marks definiteness: by adding ה־ to the beginning of the noun.

עבור usually means for, on behalf of, or for the benefit of.

In this sentence, עבור החברה suggests something like:

• for the company
• on behalf of the company

It often sounds a bit more formal than some other ways to say for in Hebrew.

Not exactly.

Both can sometimes mean for, but they are not always interchangeable.

• עבור often sounds more formal and can mean for the benefit of or on behalf of
• בשביל is often more everyday and can also mean for in the sense of for someone’s sake or intended for

In many contexts, both may be understood, but עבור החברה sounds more formal/business-like, which fits well with document and company.

Because לחברה would usually mean to the company, not for the company.

Compare:

• שלחתי את המסמך לחברה = I sent the document to the company
• שלחתי את המסמך עבור החברה = I sent the document for the company / on behalf of the company

So the choice of preposition changes the meaning:

• ל־ = to
• עבור = for / on behalf of

Hebrew word order is fairly flexible, but this order is very natural:

• שלחתי את המסמך עבור החברה

Literally: Sent-I the document for the company

Hebrew often allows the verb to come first, especially in simple statements.
But other word orders are also possible, depending on emphasis.

For example:

• אני שלחתי את המסמך עבור החברה = I sent the document for the company
  This puts more emphasis on I.

The original sentence sounds neutral and natural.

Yes, חברה (company) is a feminine noun.

In this sentence, it does not change much, because there is no adjective or verb agreeing with it directly. But in other sentences, feminine gender would matter.

For example:

• החברה גדולה = The company is big
  Here גדולה is feminine singular to match חברה.

So yes, חברה is feminine, but this particular sentence does not show much agreement.

A simple pronunciation guide is:

shaláchti et ha-mismách avúr ha-chevrá

A few notes:

• שלחתי = sha-LACH-ti
• המסמך = ha-mis-MACH
• עבור = a-VOOR or a-VUR, depending on accent/style
• החברה = ha-chev-RA

The ח sound in החברה is a throaty sound that English does not really have.

Only if the object is understood from context. In this sentence, את המסמך is the thing being sent, so it is an important part of the sentence.

You could say just:

• שלחתי עבור החברה = I sent [something] for the company

But then the listener would probably ask: What did you send?

So in the full sentence, את המסמך is there because Hebrew, like English, usually includes the object when it matters.