الفني بيكشف على العيب والكسر في الشاشة.

In Egyptian Arabic, bi- is the normal marker for the present tense in everyday statements.

So:

• يكشف = the basic imperfect form
• بيكشف = he checks / he is checking

In other words, بيكشف can describe:

• a habitual action: he checks
• a current action: he is checking

The exact meaning depends on context.

يكشف على is a set expression meaning to examine, inspect, or check.

So it is better to learn it as one chunk:

• يكشف على شخص/حاجة = check/examine a person or thing

This is important because كشف by itself often means uncover, reveal, or discover.
So على is not random here; it is part of the expression.

Because Arabic does not need a separate present-tense is in this kind of sentence.

English says:

• The technician is checking...

Egyptian Arabic simply says:

• الفني بيكشف...

The verb itself already carries the meaning, so no extra word for is is needed.

In Egyptian Arabic, الـ is usually pronounced il- or el-.

Here is how these words are typically pronounced:

• الفني → il-fanni
• العيب → el-ʿeib
• الكسر → el-kasr
• الشاشة → ish-shaasha / esh-shaasha

Why does الشاشة sound different?
Because ش is a sun letter, so the l in الـ assimilates:

• ال + شاشة → ish-shaasha

Because in normal speech, و plus الـ gets smoothed together.

So:

• و + الكسر becomes wel-kasr or wil-kasr

This is very common in spoken Arabic. Native speakers do not usually pause between the و and the noun.

Because both nouns are definite here.

Arabic usually repeats the definite article when two definite nouns are joined by و:

• العيب والكسر = the defect and the break/crack

That is the normal pattern.
If both things are specific, each noun usually gets its own الـ.

Here, العيب means the defect, the fault, or the problem.

This word is worth noticing because عيب can also mean shame or something improper in other contexts.

So:

• in technical contexts: defect / fault
• in social contexts: shame / inappropriate behavior

In this sentence, it is clearly the technical meaning.

كسر is a broad word for breakage, a break, or a fracture.

With a screen, it can refer to:

• a crack
• a broken part
• visible physical damage

So depending on context, English might translate it as crack or break.
If someone wanted to be more specific about a crack line, they might also use شرخ, but كسر is very natural for damaged screens.

Because Arabic often uses في with defects or damage inside an object or part of an object.

So في الشاشة sounds natural for:

• a defect in the screen
• a crack in the screen
• damage in the screen

By contrast, على الشاشة is more likely for something on the screen or appearing on the screen, such as:

• fingerprints on the screen
• a sticker on the screen
• text showing on the screen

English and Arabic do not always choose the same preposition.

Yes. The most natural reading is that في الشاشة applies to both nouns:

• the defect and the break/crack in the screen

So both the defect and the break are understood as being in the screen.

Something close to this:

il-fánni biyíkshif ʿala l-ʿēb wel-kásr fish-shāsha

A few connected-speech details:

• على العيب may sound like ʿalal-ʿeib
• والكسر sounds like wel-kasr
• في الشاشة often becomes fish-shaasha

So in fast natural speech, the words flow together quite a bit.