هذا مفك براغي.

A careful pronunciation is:

• هذا = hādhā
  • ذ sounds like th in this
• مفك = mifakk
• براغي = barāghī
  • غ is a deep throaty sound, often roughly compared to a French or German r

So the whole sentence is approximately:

hādhā mifakk barāghī

In very careful formal reading, you may also hear a final short vowel on مفك.

It is a nominal sentence in Arabic.

• هذا is the topic or subject-like part
• مفك براغي is the predicate, the part that identifies what the thing is

So the structure is basically:

this + screwdriver

which Arabic uses to mean this is a screwdriver.

In Arabic, the verb to be is usually not expressed in the present tense.

So Arabic says:

• هذا مفك براغي = This is a screwdriver

But in the past or future, Arabic would use forms of كان and similar verbs when needed.

This is a very common feature of Arabic, and English speakers often notice it right away.

Because مفك is masculine singular, and هذا is the demonstrative for this with masculine singular nouns.

• هذا = this for masculine singular
• هذه = this for feminine singular

Even though براغي is plural, the main noun here is مفك, so that is what controls the agreement.

It is an iḍāfa construction, often called a genitive construction.

Literally, it is something like:

• مفك = a loosening/unfastening tool
• براغي = screws

So the phrase means something like:

a tool for screws
or more literally
a loosener of screws

In normal English, of course, this is just a screwdriver.

No. Arabic does not have a separate word for a/an.

Instead, indefiniteness is usually shown by:

• the absence of الـ (the)
• and often tanwīn in fully vocalized text

Here the phrase is indefinite, so it means a screwdriver, not the screwdriver.

Normally, no. In an iḍāfa construction, the first noun usually does not take الـ.

So:

• مفك براغي = a screwdriver
• مفك البراغي = the screwdriver / a definite screwdriver phrase

That is why هذا المفك براغي is not the normal structure.

Because it is the first term of an iḍāfa.

A noun at the beginning of an iḍāfa:

• does not take tanwīn
• usually does not take الـ

So even though مفك is indefinite here, you do not see the usual indefinite ending on it.

That often surprises English-speaking learners, but it is completely normal Arabic grammar.

Because Arabic often names tools by the things they are used with, and that object can be plural.

So:

• برغي = screw
• براغي = screws

A مفك براغي is, literally, a tool for screws.

This is not very strange if you compare it to English expressions like scissors case, glasses shop, or other object-based compounds.

By itself, it normally means:

this is a screwdriver

That is because هذا is followed by an indefinite predicate.

If you want this screwdriver, you would normally say:

• هذا مفك البراغي if you want the full definite iḍāfa
• or sometimes simply هذا المفك if the context already makes clear that it is a screwdriver

So the sentence you were given is best understood as a full statement, not just a noun phrase.

It comes from the root ف-ك-ك, which has the idea of:

• loosening
• unfastening
• undoing
• taking apart

So مفك is a tool noun built from that root: a tool used to loosen or undo something.

That is why it works so naturally for screwdriver.

Yes, in ordinary written Arabic and in most everyday pronunciation, the short case endings are usually not written and often not pronounced.

So learners usually see:

هذا مفك براغي

rather than a fully vocalized version.

What matters most at this stage is:

• the sentence is a nominal sentence
• مفك is the predicate
• مفك براغي is an iḍāfa phrase

If you later study full case grammar, you will see how the endings fit into that structure.