Jeśli ktoś zemdleje w sklepie, inni klienci zwykle pomagają i robią więcej miejsca.

Because zemdleje is the perfective present form, and in Polish that form often has a future meaning.

• zemdleć / zemdleje = to faint as a single completed event
• after jeśli (if), Polish commonly uses this kind of form:
  • Jeśli ktoś zemdleje... = If someone faints...

A very important point for English speakers:

• in English, we say If someone faints
• in Polish, we also do not normally use a separate future like będzie mdleć here

So zemdleje is exactly the natural form for a one-time event in an if-clause.

Ktoś means someone or somebody.

In this sentence:

• Jeśli ktoś zemdleje... = If someone faints...

It refers to an unspecified person. It is very common in general statements like this.

Compare:

• ktoś = someone
• nikt = nobody
• każdy = everyone
• ktokolwiek = anyone at all / whoever (stronger, less common in everyday sentences like this)

So ktoś is the most natural choice here.

Because w meaning in takes the locative case when talking about location.

• dictionary form: sklep = shop/store
• locative singular: w sklepie = in the shop/store

So:

• sklep → base form
• w sklepie → after w for location

This is a very common pattern:

• w domu = in the house
• w szkole = at school / in school
• w sklepie = in the store

Because klienci refers to people, so Polish uses the masculine personal plural form of the adjective.

• singular: inny klient = another/different customer
• plural masculine personal: inni klienci = other customers

For groups of people, adjectives in the plural usually take forms like:

• dobrzy ludzie = good people
• młodzi studenci = young students
• inni klienci = other customers

If the noun were not a masculine-personal group, you would get a different plural form, such as inne.

Because this sentence describes a general habit or what usually happens, not one single event.

• zwykle = usually
• pomagają = they help / they are helping

Together:

• inni klienci zwykle pomagają = other customers usually help

In Polish, the present tense is often used for habitual statements, just like in English:

• Ludzie zwykle czekają. = People usually wait.
• Dzieci często pytają. = Children often ask.

So pomagają is correct because the sentence is talking about a repeated, typical situation.

The object is simply understood from context.

The verb pomagać usually works with the dative case:

• pomagać komuś = to help someone

So in a fuller version, you could say:

• inni klienci zwykle pomagają tej osobie
• inni klienci zwykle pomagają komuś, kto zemdlał

But because the person who fainted is already obvious from the first part of the sentence, Polish can leave it unstated:

• inni klienci zwykle pomagają = other customers usually help

This sounds natural.

robić miejsce means to make room / make space.

So:

• robią więcej miejsca = they make more room / create more space

In this context, it means people move aside so there is space around the person who fainted.

This is a normal Polish expression:

• Zrób miejsce. = Make room.
• Proszę zrobić miejsce. = Please make room.
• Robią więcej miejsca. = They make more room.

It does not mean they are physically building a place. It means clearing space.

Because here miejsce means space/room, not places/spots in a countable sense.

• więcej miejsca = more room / more space
• więcej miejsc = more places / more seats / more spots

In the sentence, the idea is:

• people move away to create more space around the person

That is why miejsce appears in the singular form miejsca here.

Also note that after więcej, Polish often uses the genitive:

• więcej czasu = more time
• więcej wody = more water
• więcej miejsca = more room

Because the first part is a subordinate if-clause, and in Polish such clauses are normally separated by a comma.

So:

• Jeśli ktoś zemdleje w sklepie, inni klienci...

This is standard Polish punctuation.

Just like:

• Jeśli pada, zostaję w domu.
• Kiedy wróci, porozmawiamy.

English punctuation can be more flexible in some cases, but in Polish this comma is expected.

Not with exactly the same meaning.

• jeśli = if
• gdy / kiedy = when

So:

• Jeśli ktoś zemdleje w sklepie... = If someone faints in a store...
• Gdy ktoś zemdleje w sklepie... = When someone faints in a store...

The difference is subtle but important:

• jeśli sounds conditional or hypothetical
• gdy/kiedy sounds more like a situation that happens when it occurs

Since this sentence describes a possible situation, jeśli is a very natural choice.

Because the sentence combines two different kinds of meaning:

1. a single completed event
2. a usual repeated reaction

So:

• zemdleje is perfective because fainting is viewed as one whole event
• pomagają and robią are imperfective because they describe what people usually do in such situations

This is very typical in Polish.

You can think of it like this:

• If X happens once, people usually do Y

Polish often expresses that as:

• Jeśli ktoś zemdleje..., ludzie pomagają...

So the mix of aspects is completely natural.

You could use other words, but klienci fits the sentence very well because the setting is a store.

• klienci = customers
• ludzie = people
• osoby = people/persons
• przechodnie = passers-by

Examples:

• inni klienci zwykle pomagają = other customers usually help
• inni ludzie zwykle pomagają = other people usually help

Using klienci makes the sentence more specific and natural for w sklepie.

Yes, Polish word order is flexible, but the original order is the most neutral.

Neutral version:

• Jeśli ktoś zemdleje w sklepie, inni klienci zwykle pomagają i robią więcej miejsca.

You could also hear variations such as:

• Jeśli ktoś zemdleje w sklepie, zwykle inni klienci pomagają i robią więcej miejsca.
• Inni klienci zwykle pomagają i robią więcej miejsca, jeśli ktoś zemdleje w sklepie.

The meaning stays almost the same, but the emphasis changes a little.

For learners, the original version is best to remember because it sounds natural and straightforward.