Strata wiosła jest problemem.

Because strata means loss, and in Polish this noun normally takes the genitive: loss of something.

• wiosło = nominative singular, oar / paddle
• wiosła = genitive singular, of the oar / paddle

So:

• strata wiosła = loss of the oar/paddle

This is very similar to English the loss of the oar.

In isolation, wiosła can indeed be:

• genitive singular of wiosło
• or nominative/accusative plural of wiosło

But in this sentence, after strata, it is understood as genitive singular.

So here it means:

• strata wiosła = loss of the oar

  not

• loss of oars

If you wanted loss of the oars, you would normally need context or a different form such as strata wioseł.

Because after jest in a sentence like X is Y, Polish often puts the second noun in the instrumental when it functions as a predicate noun.

So:

• problem = nominative
• problemem = instrumental

That is why you get:

• Strata wiosła jest problemem. = The loss of the oar is a problem.

This is a very common pattern:

• On jest lekarzem. = He is a doctor.
• To jest problemem. = This is a problem.

Yes. That is also a natural Polish sentence.

There is a useful contrast:

• Strata wiosła jest problemem.
• Strata wiosła to problem.

Both can mean The loss of the oar is a problem.

Very roughly:

• jest problemem sounds a bit more grammatical/formal/classic
• to problem is very common in everyday speech and feels a bit more direct

Both are correct.

In this sentence, jest should be included.

Polish does sometimes omit words in informal speech, but in a normal sentence like this, the present-tense form of być (to be) is usually expressed:

• Strata wiosła jest problemem.

If you want a version without jest, the usual alternative is not simple omission, but using to:

• Strata wiosła to problem.

So do not think of this as English-style The loss of the oar — a problem. Standard Polish wants either jest or to here.

Strata is in the nominative singular.

It is the subject of the sentence:

• Strata = loss
• jest problemem = is a problem

So the basic structure is:

• [subject in nominative] + jest + [predicate noun in instrumental]

That gives:

• Strata (nominative)
• wiosła (genitive, dependent on strata)
• problemem (instrumental)

Strata is correct, but it can sound a bit formal or abstract depending on context.

Another common noun is utrata:

• utrata wiosła = loss of the oar
• strata wiosła = also loss of the oar

A rough difference:

• utrata often focuses on the fact that something was lost
• strata can sound a bit more like a loss / damage / setback

In many contexts, utrata wiosła jest problemem may sound slightly more natural if you mean the event of losing it. But strata wiosła is still understandable and grammatical.

It can mean either, depending on context.

In many situations, wiosło is the general word for a rowing or paddling implement. English often distinguishes more sharply between oar and paddle than Polish does in everyday use.

So if the meaning shown to the learner is oar, that is fine. In another context, it could also be understood as paddle.

Because Polish has no articles.

So wiosła does not itself tell you whether English should be:

• the oar
• an oar
• sometimes just oar in a more general sense

The context decides.

Likewise:

• problemem can correspond to a problem or the problem, depending on context

That is completely normal in Polish.

Yes. Polish word order is more flexible than English, and changing it usually changes emphasis, not the core meaning.

For example:

• Strata wiosła jest problemem.
  Neutral: The loss of the oar is a problem.

• Problemem jest strata wiosła.
  Emphasis on problemem first, like What is the problem? The loss of the oar.

• Strata wiosła to problem.
  Very natural, direct statement.

So the original sentence is correct, but it is not the only possible order.

A rough English-friendly pronunciation is:

• vyO-swa

A few useful points:

• wi before a vowel sounds roughly like vy
• ó/o here is just normal o because the word has o
• ł sounds like English w
• so sł sounds roughly like sw

And the whole sentence can be approximated as:

• STRA-ta vyO-swa yest pro-BLE-mem

This is only an approximation, but it helps with the tricky sł / sw part.

The main noun is strata.

A good way to see this is to ask what the phrase is about:

• It is about a loss
• specifically, loss of the oar

So:

• strata = head noun
• wiosła = dependent noun in the genitive

This is the same relationship as in English:

• loss of the oar

The word oar adds information, but the core noun is still loss.