Ten klient wraca do naszego sklepu, bo sprzedawczyni zawsze cierpliwie wszystko wyjaśnia.

Ten means this or sometimes that specific in context. Polish often does not use articles like English the/a, because Polish has no articles at all.

So:

• klient = customer
• ten klient = this customer / this particular customer

Using ten makes the noun more specific. In many contexts, just klient would also be possible, but ten klient points to a particular customer the speaker has in mind.

Because ten klient is the subject of the sentence, so it is in the nominative case.

The verb wraca = returns / comes back, and the person doing that action is the subject:

• Ten klient wraca...

So we use nominative:

• ten
  • klient

Forms like tego klienta would be used in other roles, for example:

• Nie znam tego klienta. = I don’t know this customer.
  Here it is the object, not the subject.

Wraca is the 3rd person singular present tense of wracać.

It matches the subject ten klient:

• ja wracam = I return
• ty wracasz = you return
• on/ona/ono wraca = he/she/it returns

So Ten klient wraca means:

• This customer returns
• or more naturally here: This customer keeps coming back / comes back

Because the sentence describes a repeated habit, the Polish present tense works well.

This is an aspect question.

Polish verbs often come in pairs:

• wracać = imperfective
• wrócić = perfective

Here, wracać is used because the sentence describes a repeated, habitual action:

• Ten klient wraca do naszego sklepu...
  = This customer comes back to our shop / keeps returning

If you used wróci, that would normally point to a single completed return in the future:

• Ten klient wróci jutro. = This customer will come back tomorrow.

So the imperfective wraca fits the idea of regular repeated behavior.

Because the preposition do requires the genitive case.

So:

• sklep = nominative
• do sklepu = to the shop

That is why:

• nasz sklep becomes do naszego sklepu

This is very common in Polish:

• idę do domu = I’m going home
• jadę do miasta = I’m going to the city
• wracam do sklepu = I’m returning to the shop

So the change to sklepu is caused by do.

Because naszego has to agree with sklepu, which is in the genitive singular masculine after do.

Compare:

• nasz sklep = our shop
  nominative
• do naszego sklepu = to our shop
  genitive

In Polish, adjectives and possessive words change their endings to match the noun’s:

• case
• gender
• number

So naszego is simply the correct genitive form of nasz here.

Yes, but it would mean something different.

• do naszego sklepu = to our shop
  focuses on movement toward the shop
• w naszym sklepie = in our shop
  focuses on location

So:

• Ten klient wraca do naszego sklepu = This customer comes back to our shop.
• Ten klient jest w naszym sklepie = This customer is in our shop.

After wraca, do is natural when you mean returning to a place.

In standard Polish spelling, bo is usually preceded by a comma when it introduces a reason:

• Ten klient wraca do naszego sklepu, bo...

This is similar to English punctuation before because, though the rules are not always identical across the two languages.

So here the comma separates:

• the main clause: Ten klient wraca do naszego sklepu
• the reason clause: bo sprzedawczyni zawsze cierpliwie wszystko wyjaśnia

Both can mean because, but they differ a bit in style.

• bo = very common, everyday, conversational
• ponieważ = more formal or neutral in writing

In this sentence, bo sounds very natural.

So:

• Ten klient wraca..., bo... = natural everyday Polish
• Ten klient wraca..., ponieważ... = also correct, but a bit more formal

Sprzedawczyni means a female shop assistant / saleswoman / female salesperson.

It is specifically feminine. The masculine equivalent is:

• sprzedawca = male salesperson / salesman

So this sentence tells us that the person explaining things is female.

This matters grammatically because the verb form and adjective/adverb choices fit that subject, though in the present tense the verb wyjaśnia looks the same for masculine and feminine subjects.

It is in the nominative case, because it is the subject of the clause:

• sprzedawczyni zawsze cierpliwie wszystko wyjaśnia

She is the one performing the action of explaining.

So the structure is:

• sprzedawczyni = subject
• wyjaśnia = verb
• wszystko = object

Because cierpliwie is an adverb, while cierpliwa is an adjective.

Here we are describing how she explains:

• wyjaśnia cierpliwie = explains patiently

So we need an adverb.

Compare:

• cierpliwa sprzedawczyni = a patient saleswoman
  adjective describing the noun
• sprzedawczyni cierpliwie wyjaśnia = the saleswoman explains patiently
  adverb describing the verb

This is very similar to English patient vs patiently.

Wszystko means everything.

In this sentence it is the direct object of wyjaśnia:

• wyjaśnia wszystko = explains everything

Its case here is accusative. For wszystko, the accusative form looks the same as the nominative form, so there is no visible change.

Yes, Polish word order is much more flexible than English word order.

This version is natural and clear:

• sprzedawczyni zawsze cierpliwie wszystko wyjaśnia

But other orders are also possible, depending on emphasis:

• sprzedawczyni wszystko zawsze cierpliwie wyjaśnia
• sprzedawczyni cierpliwie zawsze wszystko wyjaśnia
• zawsze wszystko cierpliwie wyjaśnia

The sentence you were given sounds neutral and natural. A rough breakdown is:

• zawsze = how often
• cierpliwie = how
• wszystko = what
• wyjaśnia = verb

Polish often puts the most important or new information later, but there is no single fixed English-style order.

It can mean either in Polish, just like in English.

Here it clearly describes a habitual action:

• Ten klient wraca do naszego sklepu
  = This customer keeps coming back to our shop

and

• sprzedawczyni zawsze... wyjaśnia
  = the saleswoman always explains everything patiently

The word zawsze strongly signals repeated behavior, so we understand the sentence as a general pattern, not just one event happening at this exact moment.

Wyjaśnia means explains / clarifies.

A very similar verb is tłumaczy, which can also mean explains. In many contexts they overlap.

A rough tendency is:

• wyjaśniać = to clarify, explain something so it becomes clear
• tłumaczyć = to explain, interpret, account for; it can also mean translate

So wyjaśnia in this sentence gives the sense that the saleswoman clearly explains things to the customer.

Yes, this word can feel difficult for English speakers because it has several consonants close together.

A rough pronunciation guide is:

• sprze-daw-czy-ni

Important points:

• sprz is a consonant cluster, so say it slowly at first
• cz sounds like English ch in chop
• yni is pronounced separately at the end, roughly ih-nih, not like English ee-nee

It helps to practice it in chunks:

• sprze
• daw
• czyni

Then combine them: sprzedawczyni.

Because Polish does not have articles like the and a/an.

English says:

• the customer
• the shop
• a saleswoman

Polish usually just uses the noun alone, or adds another word if needed for specificity:

• klient
• sklep
• sprzedawczyni
• ten klient = this particular customer

So Polish expresses definiteness in other ways, such as context, word order, or demonstratives like ten.