Jeśli znowu będziemy robić nadgodziny w piątek, nie zdążę na szkolenie.

That is a normal difference between Polish and English.

In Polish, when the condition is about the future, you can use the future tense in the jeśli clause:

Jeśli znowu będziemy robić nadgodziny w piątek, nie zdążę na szkolenie.

So Polish says, literally, something like:

If we will be doing overtime again on Friday, I won’t make it to the training.

This is correct in Polish. English and Polish simply handle future conditions differently.

Yes. Jeśli and jeżeli both mean if.

In most everyday situations, they are interchangeable:

• Jeśli znowu będziemy robić nadgodziny...
• Jeżeli znowu będziemy robić nadgodziny...

Jeżeli can sound a little more formal or careful, but the difference is small.

Będziemy robić is the future of the imperfective verb robić.

It is used here because the sentence talks about an activity in progress or a repeated/extended situation: doing overtime, not one neatly completed action.

• będziemy robić nadgodziny = we’ll be doing / working overtime
• zrobimy nadgodziny would sound more like we’ll do/complete some overtime, which is less natural here

So będziemy robić fits the idea better: if overtime happens again on Friday, then the speaker won’t make it to the training.

Literally, yes, robić means to do/make, but the whole expression robić nadgodziny is an idiomatic way to say work overtime.

So:

• robić nadgodziny = to work overtime
• nadgodziny = overtime hours

Polish often uses robić in expressions where English would use a different verb.

Because in Polish, overtime is commonly thought of as overtime hours, so the plural is standard.

• nadgodzina = one overtime hour
• nadgodziny = overtime / overtime hours

That is why robić nadgodziny is the usual phrase.

With days of the week used as time expressions, Polish normally uses w + accusative:

• w poniedziałek = on Monday
• w czwartek = on Thursday
• w piątek = on Friday

So w piątek is the correct form for on Friday.

This is worth remembering because w often takes the locative in other situations, but with days of the week in this kind of time expression, you usually get forms like w piątek.

Because Polish usually drops subject pronouns when they are not needed.

The verb endings already show who is meant:

• będziemy = we will
• zdążę = I will / I’ll manage

So:

• Jeśli znowu będziemy robić nadgodziny w piątek, nie zdążę na szkolenie.

already clearly means:

• If we... , I won’t...

You could add my or ja, but that would usually add emphasis:

• Jeśli my znowu będziemy robić nadgodziny...
• ja nie zdążę na szkolenie

Zdążę comes from zdążyć, which means something like:

• to make it in time
• to manage to get somewhere before it starts / before it is too late

So nie zdążę na szkolenie means:

• I won’t make it to the training in time
• I won’t get to the training on time

It is not just about physical movement. It is about being too late for something.

Because zdążyć is a perfective verb.

In Polish, perfective verbs do not have a normal present tense. Their present-looking forms actually refer to the future:

• zdążę = I will make it in time
• nie zdążę = I won’t make it in time

So even though zdążę looks like a present-tense form, its meaning here is future.

Using będę zdążać would involve the imperfective verb zdążać, which is not what you want here. The sentence is about a single result: either I make it in time, or I don’t.

It is na + accusative.

After zdążyć, Polish often uses na when talking about arriving in time for an event, transport, meeting, class, and so on:

• zdążyć na pociąg = make the train
• zdążyć na spotkanie = make it to the meeting
• zdążyć na szkolenie = make it to the training

Szkolenie is a neuter noun, and in the singular its nominative and accusative forms look the same, so you see:

• nominative: szkolenie
• accusative: szkolenie

Yes. Polish word order is flexible, and znowu can move depending on emphasis.

The given sentence:

• Jeśli znowu będziemy robić nadgodziny w piątek, nie zdążę na szkolenie.

Possible alternatives:

• Jeśli będziemy znowu robić nadgodziny w piątek, nie zdążę na szkolenie.
• Jeśli będziemy robić nadgodziny znowu w piątek, nie zdążę na szkolenie.

The first version is the most natural. Putting znowu earlier often makes the again idea sound more natural and prominent.

Because Polish normally separates the jeśli clause from the main clause with a comma.

So:

• Jeśli znowu będziemy robić nadgodziny w piątek, nie zdążę na szkolenie.

This is standard punctuation in Polish for this kind of complex sentence.

It is a real or possible future condition.

Jeśli introduces a condition that the speaker sees as possible:

• If we end up working overtime again on Friday, I won’t make it...

If Polish wanted a more hypothetical or less realistic idea, it would often use gdyby with conditional forms instead:

• Gdybyśmy znowu robili nadgodziny w piątek, nie zdążyłbym / nie zdążyłabym na szkolenie.

So the original sentence sounds like a realistic possibility, not an unreal fantasy.