Nie musisz iść pieszo, możemy jechać autobusem.

In Polish, nie musisz usually means there is no necessity: you don’t have to.

• Musisz = you have to / you must
• Nie musisz = you don’t have to

If you want to say you must not / you are not allowed to, Polish usually uses something like:

• nie możesz = you can’t / you’re not allowed to
• nie wolno ci = you must not / you are not allowed to

So in this sentence, nie musisz iść pieszo means there is another option, not a prohibition.

Musisz is the 2nd person singular form of the verb musieć (to have to / must).

So:

• muszę = I have to
• musisz = you have to
• musi = he/she/it has to

In the sentence, musisz matches an understood singular you.

Polish distinguishes how you move:

• iść = to go on foot / to walk
• jechać = to go by vehicle such as a bus, car, train, bike, etc.

So the contrast is very natural:

• iść pieszo = go on foot
• jechać autobusem = go by bus

In English, go can cover both ideas, but Polish often chooses a more specific motion verb.

Yes, a little — but it is still natural.

Because iść already suggests movement on foot, pieszo adds emphasis and contrast:

• Nie musisz iść = You don’t have to go
• Nie musisz iść pieszo = You don’t have to go on foot

Here pieszo highlights the contrast with autobusem in the second clause.

Pieszo is an adverb meaning on foot.

Examples:

• Idę pieszo. = I’m going on foot.
• Wrócimy pieszo. = We’ll come back on foot.

A common learner mistake is trying to say na pieszo. In standard Polish, pieszo is the normal form. You may also hear na piechotę, which is a common alternative.

Because the speaker is first talking about you, then suggesting a plan for both of us.

• Nie musisz iść pieszo = You don’t have to walk
• możemy jechać autobusem = we can go by bus

This is very natural in conversation: first remove the necessity, then offer a shared option.

Polish often leaves subject pronouns out because the verb ending already shows the person.

• musisz already means you have to
• możemy already means we can

So:

• Nie musisz iść pieszo sounds natural
• My możemy jechać autobusem is possible, but my would add emphasis, like we can go by bus

English needs pronouns much more often than Polish does.

Because after jechać to express the means of transport, Polish uses the instrumental case.

So:

• autobus = dictionary form
• autobusem = instrumental form

Compare:

• jechać autobusem = go by bus
• jechać pociągiem = go by train
• jechać samochodem = go by car

This is a very common pattern in Polish.

Yes, absolutely.

• jechać is imperfective
• pojechać is perfective

In this sentence:

• możemy jechać autobusem sounds neutral: we can go by bus
• możemy pojechać autobusem can sound a bit more like we can take the bus / make the trip by bus

Both are natural. For many learners at first, the key point is simply that both are possible, with a slight aspect difference.

The comma is natural because there are two clauses:

• Nie musisz iść pieszo
• możemy jechać autobusem

Polish word order is fairly flexible, so you could also say:

• Możemy jechać autobusem, nie musisz iść pieszo.

That changes the emphasis a little:

• first version: first remove the necessity, then offer the solution
• second version: first offer the solution, then explain why

Both are understandable.

Iść is one of the trickier Polish words for English speakers.

A rough guide:

• iść sounds approximately like eeshch, but with a very soft Polish consonant sound at the end
• musisz ≈ MOO-shish with softer Polish ś
• jechać ≈ YE-khahch
• autobusem ≈ ow-toh-BOO-sem

Also, Polish stress is usually on the second-to-last syllable:

• au-to-BU-sem
• MU-sisz
• JE-chać

The hardest part here is the cluster in iść, so it helps to listen to native audio and repeat it slowly.