انا قررت اتعلم سباحة في النادي ده اول ما ييجي الصيف.

In Egyptian Arabic, the initial أ of first-person present verbs is often not written in informal spelling, even though it is still pronounced.

So:

• اتعلم = أتعلم
• both mean I learn / I’m learning

In Egyptian pronunciation, this is usually something like atʿallam.

This kind of spelling is very common in chats, subtitles, and informal writing.

It means learn swimming, which in natural English is usually learn to swim.

Here, سباحة is a verbal noun meaning swimming. Egyptian Arabic often uses a noun like this after اتعلم.

So:

• اتعلم سباحة = learn swimming / learn how to swim
• very natural English translation: learn to swim

A very common alternative in Egyptian would also be:

• اتعلم أعوم = learn to swim

Because Arabic does not always use a separate word equivalent to English to before another verb.

In Egyptian Arabic, قررت can be followed directly by another verb:

• قررت اتعلم = I decided to learn

So the structure is normal:

• أنا قررت اتعلم...

You do not need an extra word between قررت and اتعلم.

Both can work, but the indefinite form is very natural in Egyptian Arabic in this kind of sentence.

• اتعلم سباحة = learn swimming
• اتعلم السباحة = learn swimming / learn how to swim

The version without ال can sound a bit lighter and more colloquial. The version with ال may sound a little more explicit or slightly closer to more formal Arabic, but both are understandable and natural.

Because in Egyptian Arabic, demonstratives like ده usually come after the noun.

So:

• النادي ده = this club
• literally: the club this

This is one of the first word-order differences English speakers notice.

Compare:

• البيت ده = this house
• العربية دي = this car

The preposition في often covers both in and at in English.

So:

• في النادي ده can mean in this club or at this club

In this sentence, natural English is:

• at this club

That is very normal. Arabic often uses في where English would prefer at.

أول ما is a very common expression meaning:

• as soon as
• when
• once

So:

• اول ما ييجي الصيف = as soon as summer comes
• or when summer comes

It introduces a time clause.

ييجي means he comes / it comes, from the verb جِه / ييجي in Egyptian Arabic.

In this sentence, الصيف (summer) is treated grammatically like something that comes:

• ييجي الصيف = summer comes

English also does this sometimes:

• when summer comes

So this part is very natural.

Because after time expressions like أول ما, Arabic often uses the present tense to refer to a future event.

So:

• اول ما ييجي الصيف literally looks like as soon as summer comes
• but it refers to the future: when summer comes

This is similar to English, which also often uses the present after when:

• not usually when summer will come
• but when summer comes

So this works very similarly to English here.

Because after expressions like أول ما, Egyptian Arabic often does not need a future marker such as حـ or هــ.

So:

• اول ما ييجي الصيف = natural
• literally: as soon as summer comes

The future meaning is already clear from the time expression.

In Arabic, seasons are often used with the definite article:

• الصيف = the summer / summer
• الشتا = the winter
• الربيع = the spring

Even when English would just say summer, Arabic often says الصيف.

So ييجي الصيف is the normal way to say summer comes.

Yes. It could be omitted because قررت already shows first person singular.

So both are possible:

• أنا قررت اتعلم سباحة...
• قررت اتعلم سباحة...

Including أنا can add a little emphasis or clarity, but it is not required.

Yes, it is natural and understandable. But there are a few common alternatives.

For example:

• أنا قررت أتعلم السباحة في النادي ده أول ما ييجي الصيف
• أنا قررت أتعلم أعوم في النادي ده أول ما ييجي الصيف

The second one, with أعوم, is especially conversational for learn to swim.

So the original sentence is good, but there are other natural ways to say the same thing.

A rough pronunciation guide would be:

• ana arrart atʿallam seba7a fin-nādi da awwal ma yigī ṣ-ṣēf

A few helpful notes:

• قررت has a doubled r sound
• ده sounds like da
• ييجي sounds roughly like yigī
• الصيف is often pronounced with a strong s sound at the start because of the ص

This is only an approximation, but it can help you get started.