بابا ركب اوتوبيس امبارح.

A simple learner-friendly pronunciation is:

Bāba ركِب otobīs embāreḥ.

A few notes:

• بابا = bāba
• اوتوبيس = otobīs
• امبارح = embāreḥ or imbāriḥ, depending on accent/transliteration style

Also, Arabic script normally does not write short vowels, so you may see the same spelling transliterated slightly differently in different books.

بابا is a very common Egyptian Arabic word for dad or papa. Adults absolutely use it in normal everyday speech.

It is more natural in conversation than the more formal word أب. So in Egyptian Arabic, بابا is not strange or overly childish in family contexts.

ركب is the past tense verb, in the 3rd person masculine singular form.

That means it matches a subject like بابا.

So the grammar is basically:

• بابا = the subject
• ركب = rode / got on / took / boarded

In Egyptian Arabic, this verb is often used with vehicles.

Because the verb already shows the person, gender, and number.

In ركب, the verb itself tells you the subject is:

• 3rd person
• masculine
• singular

Since the sentence already has the noun بابا, adding a separate pronoun like he would be unnecessary.

In Egyptian Arabic, with the verb ركب, the vehicle is often a direct object.

So Arabic says something closer to:

• rode a bus
• boarded a bus
• took a bus

rather than rode on a bus.

That is normal Arabic usage, even though English often uses a preposition in similar situations.

Because Arabic does not use a separate word for a / an.

A noun without الـ is usually indefinite, so اوتوبيس can mean a bus.

Compare:

• اوتوبيس = a bus
• الأوتوبيس = the bus

So the idea of indefiniteness is built into the noun form, not expressed by a separate article.

No, it is a loanword that came into Arabic from a European source related to autobus.

That is very common in Egyptian Arabic, especially for modern objects and transportation.

Even though it is a loanword, it is completely normal everyday Egyptian vocabulary.

امبارح means yesterday.

Yes, it is a common Egyptian Arabic word. It is not the usual Modern Standard Arabic form.

So this sentence is clearly colloquial Egyptian, not formal written Arabic.

Yes, it can move.

Putting امبارح at the end is very normal in Egyptian Arabic:

• بابا ركب اوتوبيس امبارح

But you can also front it for emphasis or topic-setting:

• امبارح بابا ركب اوتوبيس

Both are fine. The end position is just a very natural neutral word order.

Yes, that is possible.

Egyptian Arabic allows more than one word order. For example:

• بابا ركب اوتوبيس امبارح
• ركب بابا اوتوبيس امبارح

The version starting with بابا feels very natural when Dad is the topic.
The version starting with the verb can sound a bit more narrative or event-focused.

So both can be grammatical, but the first one is often easier for learners and very common in speech.

A very natural Egyptian Arabic negative is:

بابا ما ركبش اوتوبيس امبارح.

This uses the common Egyptian negation pattern:

• ما ... ش

So:

• ركب = he rode / took
• ما ركبش = he didn’t ride / didn’t take

That pattern is one of the most important features of Egyptian Arabic.

Usually, in everyday Egyptian Arabic, you can just use intonation:

بابا ركب اوتوبيس امبارح؟

So the word order may stay the same, and your voice rising at the end shows it is a question.

Using هل would sound formal or Modern Standard Arabic rather than normal casual Egyptian speech.

The verb would change to match the new subject.

For example:

• ماما ركبت اوتوبيس امبارح. = Mom took a bus yesterday.
• هم ركبوا اوتوبيس امبارح. = They took a bus yesterday.

So here the key idea is agreement:

• ركب = masculine singular
• ركبت = feminine singular
• ركبوا = plural

That is why ركب fits بابا in the original sentence.