بينما أشد البرغي، ينظر أبي إلى المطرقة.

بينما means while and introduces an action that is happening at the same time as another action.

So in:

بينما أشد البرغي، ينظر أبي إلى المطرقة

the idea is:

• I am tightening the screw
• at the same time, my father is looking at the hammer

It connects the two parts as overlapping actions.

A learner will often compare these two:

• بينما = while
• عندما = usually when

In many contexts they can both introduce time clauses, but بينما more clearly suggests simultaneity, so it fits very naturally when two actions are going on at once.

It is built into the verb.

أشد means I tighten or I am tightening. The prefix أ- marks first person singular in the present tense.

So Arabic often does not need a separate word for I. You could say أنا أشد for emphasis, but normally أشد by itself is enough.

Because Arabic commonly uses the present/imperfect to describe actions that are happening now, are ongoing, or are habitual.

Here:

• أشد = I tighten / I am tightening
• ينظر = he looks / he is looking

With بينما, the present tense is very natural because the sentence describes two simultaneous actions.

It comes from the verb شدّ, which means to tighten, to pull tight, or to fasten firmly.

Its root is:

• ش د د

This is a doubled/geminate verb, because the second and third root consonants are the same.

The fully vocalized present-tense form here is:

أَشُدُّ

In normal Arabic writing, the short vowels and the shadda are often omitted, so you simply see أشد.

Because البرغي is the direct object of the verb أشد.

The verb شدّ can take an object directly:

• شدّ البرغي = he tightened the screw

So there is no need for a preposition such as to or at here.

In fully marked Arabic, البرغي would be in the accusative case because it is the direct object.

Because نظر إلى is the normal way to say to look at in Arabic.

So:

• ينظر أبي إلى المطرقة = my father looks at the hammer

This is something English speakers have to learn as a verb-preposition combination. The preposition is part of the usual expression.

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

So:

• ينظر أبي إلى المطرقة

is a normal VSO pattern:

• verb: ينظر
• subject: أبي

Arabic can also use:

• أبي ينظر إلى المطرقة

That is also correct, but it feels more like my father is being highlighted or made more prominent.

Because Arabic usually shows possession by adding a suffix to the noun.

Here:

• أب = father
• أبي = my father

The -ي ending means my.

So instead of using a separate word like English my, Arabic often attaches the possessive directly to the noun.

Because Arabic usually uses attached pronouns for possession.

For example:

• أبي = my father
• أبوك = your father
• أبوه = his father

So in this sentence, أبي already includes both the noun father and the meaning my.

A fully vocalized version would be:

بَيْنَما أَشُدُّ البُرْغِيَّ، يَنْظُرُ أَبِي إِلَى المِطْرَقَةِ.

This helps show the grammar more clearly:

• أَشُدُّ = first person singular present
• البُرْغِيَّ = direct object, so accusative
• يَنْظُرُ = third person masculine singular present
• إِلَى المِطْرَقَةِ = after a preposition, so genitive

Either can be correct.

Arabic present/imperfect does not force the same distinction that English does between:

• looks
• is looking

So ينظر can mean either one, depending on context. In a sentence with بينما, English often prefers is looking, because the action is happening at the same time as I am tightening.