Daję sukienkę w zamian za bluzkę.

Daję is the 1st person singular present tense form of dawać (to give, imperfective).

So it means:

• I give
• I am giving

The ending -ę tells you the subject is I, which is why Polish does not need a separate word for I here.

Because sukienkę is the direct object of daję.

The dictionary form is sukienka (dress), but after the verb daję, it goes into the accusative singular:

• sukienka → sukienkę

This is a very common pattern for feminine singular nouns ending in -a:

• bluzka → bluzkę
• książka → książkę
• kawa → kawę

Because the phrase w zamian za is followed by the accusative.

So:

• bluzka = dictionary form
• bluzkę = accusative singular

Even though bluzkę is not the direct object of daję, it still changes because it comes after za in this expression:

• w zamian za bluzkę = in exchange for a blouse

W zamian za means in exchange for or in return for.

It is best learned as a fixed expression:

• w zamian za coś = in exchange for something

So:

• Daję sukienkę w zamian za bluzkę = I’m giving a dress in exchange for a blouse

Because Polish often omits subject pronouns when they are clear from the verb form.

In daję, the ending already tells us the subject is I.

So:

• Daję sukienkę... = I give / I am giving a dress...
• Ja daję sukienkę... is also possible, but ja adds emphasis, contrast, or emotion.

For example:

• Ja daję sukienkę, a ty bluzkę. = I’m giving the dress, and you the blouse.

It can mean both.

Polish present tense often covers what English expresses with:

• I give
• I am giving

The exact meaning depends on context.

Here, daję could mean:

• I give a dress in exchange for a blouse
• I’m giving a dress in exchange for a blouse

If the speaker is talking about a current exchange, English will often prefer I’m giving.

Because dawać is imperfective, and its present tense form daję can describe a present action.

Polish aspect matters:

• dawać = imperfective
• dać = perfective

The perfective verb dać does not normally have a true present meaning. Its form dam means:

• I will give

So compare:

• Daję sukienkę... = I give / I’m giving a dress...
• Dam sukienkę... = I will give a dress...

No, Polish word order is fairly flexible.

The given sentence is a natural neutral order:

• Daję sukienkę w zamian za bluzkę.

But you can move parts around for emphasis:

• Sukienkę daję w zamian za bluzkę.
  Emphasizes the dress
• W zamian za bluzkę daję sukienkę.
  Emphasizes the exchange condition

The meaning stays basically the same, but the focus changes.

Because Polish has no articles.

So sukienkę can mean:

• a dress
• the dress

And bluzkę can mean:

• a blouse
• the blouse

Context tells you which meaning is intended.

That is why one Polish sentence can correspond to several English versions.

Not always. Za can take different cases depending on meaning.

But in this sentence, the important thing is:

• w zamian za + accusative

So you should learn this pattern as:

• w zamian za bluzkę
• w zamian za pomoc
• w zamian za pieniądze

In this expression, za is followed by the accusative.

Yes. A common alternative is:

• Wymieniam sukienkę na bluzkę.

This also means something like:

• I’m exchanging a dress for a blouse

The sentence you were given is a bit more literally:

• I’m giving a dress in exchange for a blouse

So both can work, but they present the exchange slightly differently.