يبشر صديقي المكون بالمبشرة.

Because verb-first word order is very common in Modern Standard Arabic.

So the sentence is arranged as:

verb + subject + object + prepositional phrase

Literally, it is closer to:

Grates my friend the ingredient with the grater.

In natural English, we usually switch that to:

My friend grates the ingredient with the grater.

Arabic can also use subject-first order, but verb-first is very normal.

In a verb-first sentence, the noun that comes right after the verb is usually the subject, the doer of the action.

So here:

• يبشر = grates
• صديقي = my friend
• المكون = the ingredient / component

That makes صديقي the one doing the grating.

If the sentence were fully vowelled, المكوّنَ would show the accusative ending of the direct object, while صديقي is grammatically nominative as the subject, even though that is not visibly marked here.

The ـي means my.

• صديق = friend
• صديقي = my friend

This is an attached possessive pronoun. Arabic often expresses possession by attaching the pronoun directly to the noun.

Because a noun with a possessive suffix is already definite.

So:

• صديق = a friend / friend
• صديقي = my friend

You do not say الصديقي for my friend. The my already makes it specific.

Here المكون most naturally means the ingredient or the component.

In a cooking context, ingredient is usually the best translation.

Without short vowels, المكون can be read in more than one way, but the context here points to المُكَوِّن as the intended word.

So in this sentence it is the thing being grated.

The preposition بـ often means with, by, or by means of.

Here it marks the instrument used to do the action:

• بالمبشرة = with the grater

Also note:

• بـ + الـ becomes بالـ

So بالمبشرة is literally with the grater.

Yes. In this sentence, they come from the same root ب-ش-ر in the sense of grating.

• يبشر = he grates / grates
• مبشرة = grater

This is very common in Arabic: a verb and the tool used for that action can come from the same root.

A useful warning, though: the same consonants بشر can also appear in words related to good news, depending on the vowel pattern. So context matters a lot in unvowelled Arabic writing.

Because they are definite:

• المكون = the ingredient / component
• المبشرة = the grater

This usually means the speaker and listener already know which ingredient and which grater are being talked about.

In context, Arabic often uses الـ this way for items that are already identifiable.

One likely reading in this context is:

يَبْشُرُ صَديقي المُكَوِّنَ بِالمِبْشَرَةِ

Since normal Arabic writing usually leaves out short vowels, the bare spelling يبشر صديقي المكون بالمبشرة can look ambiguous until context tells you how to read it.

Yes. That would also be a correct sentence.

The difference is mainly word order and emphasis:

• يبشر صديقي المكون بالمبشرة = more typically verb-first
• صديقي يبشر المكون بالمبشرة = subject-first, often with a bit more focus on my friend

Both are possible in Modern Standard Arabic.