لا حد في البيت ولا حد في الشارع شاف المفتاح.

In Egyptian Arabic, حد means a person / anyone / someone, depending on context.

In this sentence:

• لا حد = no one / nobody
• ولا حد = and no one / nor anyone

So حد is the basic word for person/anyone, and the negatives around it give it the meaning nobody.

It is also the everyday colloquial counterpart of MSA أحد.

This is the Egyptian Arabic equivalent of neither ... nor ....

• لا حد في البيت = no one in the house
• ولا حد في الشارع = nor anyone in the street

Here, ولا is basically و + لا:

• و = and
• لا = not / no

So the sentence builds a paired negative structure:

• لا ... ولا ... = neither ... nor ...

Because the sentence is already negative through لا حد and ولا حد.

English does the same thing:

• No one saw the key
• not No one didn’t see the key

So in Arabic, once you have no one / nobody as the subject, the verb itself does not need separate negation here.

That is why:

• شاف المفتاح = saw the key

is correct after لا حد ... ولا حد ...

Because حد is treated grammatically as singular, and masculine singular is the default form when the gender is unknown, mixed, or not important.

So even though the meaning is about people in general, the verb stays in the default singular masculine form:

• شاف = he saw

In context, it means saw with no one as the subject.

If you were clearly talking only about women in a different kind of sentence, you might see feminine agreement, but here شاف is the normal choice.

شاف is the past tense form, meaning saw.

It comes from the verb:

• يشوف = to see

So:

• شاف = he saw
• يشوف = he sees / to see

In this sentence, the event is completed, so the past tense is used.

Egyptian Arabic has flexible word order, and this order is very natural when the speaker wants to set up the two groups first, then say what happened.

So the structure is:

• لا حد في البيت
• ولا حد في الشارع
• شاف المفتاح

This feels like:

• Neither anyone in the house nor anyone in the street saw the key

Putting شاف المفتاح at the end lets the sentence build up before delivering the main action.

في is a very common preposition meaning in, at, or sometimes on, depending on context.

Here:

• في البيت = in the house / at home
• في الشارع = in the street / on the street

Arabic uses في more broadly than English, so you should not expect a separate word for every English preposition choice.

The word الشارع is pronounced with assimilation because ش is a sun letter.

So الشارع is not pronounced as a full el-shaariʿ with a clear l sound. Instead, the l of ال merges into the sh sound.

A rough pronunciation is:

• ish-shāreʿ or esh-shāreʿ

And in connected speech:

• في الشارع often sounds like fish-shāreʿ

This is a normal sound rule in Arabic with sun letters.

Because the sentence refers to a specific key that is already known in the conversation.

• المفتاح = the key
• مفتاح = a key

So the definite article ال shows that this is not just any key, but the key.

It is clearly Egyptian colloquial in style.

The biggest clue is حد, which is everyday spoken Egyptian. In MSA, you would normally use أحد instead.

A more MSA-like version would be:

• لا أحد في البيت ولا أحد في الشارع رأى المفتاح

So the given sentence is the kind of structure a learner should associate with spoken Egyptian, not formal standard Arabic.

Yes. In everyday speech, محدّش and مافيش حد are both very common ways to say nobody / no one.

However, this sentence uses a nice paired pattern:

• لا ... ولا ...

which matches English neither ... nor ...

So while محدّش is very common in general, the form in your sentence works well because it balances the two locations:

• no one in the house
• nor anyone in the street

That makes the sentence sound structured and clear.