Jutro rano mamy obowiązkowe szkolenie, więc każdy pracownik musi być na czas.

Because Polish often expresses time with simple adverbial phrases, without extra words like on or in.

• jutro = tomorrow
• rano = in the morning / morning

So jutro rano literally looks like tomorrow morning, just like in natural English.

The order jutro rano is the most neutral and common one. You might sometimes hear other word orders in context, but jutro rano is the standard phrase to learn.

In Polish, mieć (to have) is very commonly used for scheduled events, classes, meetings, duties, and similar things involving a group.

So:

• mamy szkolenie = we have training / we’ve got training

This sounds very natural in Polish.

A different sentence like Jutro rano jest obowiązkowe szkolenie is also possible, but it shifts the focus more to the existence of the event itself: There is mandatory training tomorrow morning.

So:

• mamy obowiązkowe szkolenie = more personal, from the group’s point of view
• jest obowiązkowe szkolenie = more impersonal, announcing the event

Because obowiązkowe has to agree with szkolenie.

• szkolenie is a neuter singular noun
• adjectives must match the noun in gender, number, and case

So:

• obowiązkowy = base dictionary form
• obowiązkowe szkolenie = mandatory training

Here the adjective is neuter singular to match szkolenie.

It is in the accusative, because it is the direct object of mamy (we have).

However, for many neuter nouns, the nominative and accusative forms are identical. So although this is accusative in function, the form still appears as:

• szkolenie

That is why it looks unchanged.

Because każdy means each / every, and in Polish it normally takes:

• a singular noun
• a singular verb

So:

• każdy pracownik musi = every employee must

Even though the meaning refers to many people, the grammar is singular.

Compare:

• każdy pracownik musi = every employee must
• wszyscy pracownicy muszą = all employees must

Both are correct, but they are built differently.

Because after the modal verb musieć (must / have to), Polish normally uses the infinitive of the next verb.

So:

• musi = must
• być = to be

Together:

• musi być = must be

This is very similar to English:

• must be
• must come
• must work

Examples:

• Muszę iść. = I must go.
• Muszą czekać. = They must wait.
• Każdy pracownik musi być na czas. = Every employee must be on time.

Na czas is a fixed expression meaning on time.

So:

• być na czas = to be on time
• przyjść na czas = to arrive on time

In your sentence, musi być na czas means the employee must be punctual / must be there on time.

This expression is idiomatic, so it is best learned as a set phrase.

Here czas is in the accusative after the preposition na.

The phrase na czas is fixed and idiomatic, so learners usually memorize it as a whole. It is not something you would normally translate word-for-word.

A useful point:

• na czas = on time
• w porę = in time

These are similar, but not always identical in use.

Więc means so, therefore, or thus. It connects the two parts of the sentence:

• Jutro rano mamy obowiązkowe szkolenie
• więc każdy pracownik musi być na czas

So the logic is:

We have mandatory training tomorrow morning, so every employee must be on time.

It is a very common linking word in everyday Polish.

Yes. Polish word order is more flexible than English word order, because grammatical endings carry a lot of information.

Your sentence has a very neutral, natural order:

• Jutro rano mamy obowiązkowe szkolenie, więc każdy pracownik musi być na czas.

But Polish can move elements around for emphasis. For example:

• Każdy pracownik musi być na czas, bo jutro rano mamy obowiązkowe szkolenie.

That changes the flow and emphasis, but not the core meaning.

For learners, the original version is a good standard model.

Polish does not have articles like a, an, or the.

So:

• obowiązkowe szkolenie can mean a mandatory training session or the mandatory training session
• każdy pracownik means every employee

Polish usually leaves definiteness to context. That is completely normal. English speakers often look for articles, but in Polish they simply are not there.