Dopiero teraz rozumiem ten problem.

Here dopiero means something like only, just now, or not until.

So Dopiero teraz rozumiem ten problem has the sense of:

• Only now do I understand this problem
• I’m only now understanding this problem
• It’s only now that I understand this problem

It adds the idea that before this moment, the speaker did not understand it.

They do both relate to time, but they do different jobs:

• teraz = now
• dopiero = only / not until

Together, dopiero teraz means only now.

If you said just Teraz rozumiem ten problem, it would mean Now I understand this problem, but it would not stress so strongly that the understanding happened late or only at this point.

So dopiero teraz is more emphatic and more specific.

Rozumiem is the 1st person singular present tense of rozumieć = to understand.

Even though English might sometimes say Now I finally understood it in some contexts, Polish often uses the present tense here to describe a current state:

• rozumiem = I understand

The speaker is saying that understanding is true now.

If you wanted to focus on the moment when understanding happened, Polish might use a past perfective form, for example:

• Dopiero teraz zrozumiałem / zrozumiałam ten problem
  = Only now have I come to understand this problem / Only now did I realize this problem

That version highlights the change more strongly.

This is an aspect question, which is very important in Polish.

• rozumieć = to understand
  imperfective; describes a state or ongoing understanding
• zrozumieć = to come to understand / to understand completely
  perfective; describes reaching understanding

So:

• Dopiero teraz rozumiem ten problem
  focuses on the fact that now the understanding exists
• Dopiero teraz zrozumiałem / zrozumiałam ten problem
  focuses on the moment of finally grasping it

Both are natural, but they are not exactly the same.

Because problem is the direct object of rozumiem.

The verb rozumieć takes the accusative case:

• rozumiem co? = I understand what?
• ten problem

Now here is the useful detail: problem is a masculine inanimate noun, and in Polish, masculine inanimate nouns often have the same form in nominative and accusative singular.

So:

• nominative: ten problem
• accusative: ten problem

That is why the form does not change.

Literally, ten means this.

So ten problem literally means this problem.

However, Polish has no articles like the and a/an, so sometimes a demonstrative like ten can sound more natural in places where English would simply say the.

Depending on context, ten problem may feel like:

• this problem
• that problem we’re talking about
• sometimes almost like the problem

So the exact English translation depends on context, even though the Polish form is the same.

Yes, you can, but the nuance changes.

• Dopiero teraz rozumiem ten problem
  = Only now do I understand this problem / that specific problem
• Dopiero teraz rozumiem problem
  = more general, less anchored to a specific previously mentioned problem

In many contexts, Polish speakers would prefer ten problem if they mean a particular problem already known in the conversation.

So ten helps point to a specific thing.

Yes. Polish word order is fairly flexible, and changing it often changes emphasis rather than basic meaning.

Possible variants include:

• Dopiero teraz rozumiem ten problem.
• Teraz dopiero rozumiem ten problem.
• Ten problem dopiero teraz rozumiem.
  This is much more marked and used for emphasis.

The most neutral version here is the original one.

A very common alternative is:

• Teraz dopiero rozumiem ten problem.

This often sounds especially natural in speech, with emphasis on now, only now.

Yes. Problem is a masculine noun in Polish.

That is why it goes with:

• ten problem
  not
• ta problem
• to problem

This is also why, in the accusative singular, it stays the same as the nominative, because it is masculine inanimate.

A helpful rough pronunciation is:

• ro-ZOO-myem

A few notes:

• stress in Polish usually falls on the second-to-last syllable
• so in rozumiem, the stress is on -zu-
• rz is pronounced like the zh sound in measure
• ie after a consonant often sounds like a ye glide

So rozumiem is approximately:

• ro-ZHU-myem

That is only an approximation, but it is a useful start.

Yes, absolutely. It is a very natural sentence.

A Polish speaker might use it when:

• something has finally become clear
• they have been thinking about an issue for a while
• someone has just explained something successfully

For example, after a long explanation, someone might say:

• A, dopiero teraz rozumiem ten problem.
  = Ah, only now do I understand the problem.

So this is not a textbook-only sentence; it is something people could genuinely say.