Mâine merg din nou la poștă ca să trimit o scrisoare.

In Romanian, the present tense is often used for a planned future action, especially when there is a time word like mâine (tomorrow).

So:

• Mâine merg la poștă = Tomorrow I’m going to the post office
• Literally, it looks like Tomorrow I go to the post office, but in natural English we usually say I’m going or I’ll go

Romanian can also use an explicit future form, such as voi merge, but merg sounds very natural here.

Romanian often drops subject pronouns when the verb already makes the subject clear.

• merg already means I go / I’m going
• So eu merg and merg both mean I go, but eu is usually only added for emphasis or contrast

For example:

• Merg la poștă = I’m going to the post office
• Eu merg, nu el = I’m going, not him

Din nou means again or anew.

So:

• merg din nou = I’m going again

It is a very common expression. Romanian also has iar and iarăși, which can also mean again, but din nou is very straightforward and neutral.

La poștă means to the post office.

In Romanian, some places and institutions are commonly referred to without the definite article after prepositions like la:

• la școală = to school
• la bancă = to the bank
• la poștă = to the post office

You may also hear la poșta in certain specific contexts, but la poștă is the standard, natural expression for going to the post office as a place/service.

Ca să means in order to / so that and introduces a purpose.

So:

• Merg la poștă ca să trimit o scrisoare
• = I’m going to the post office in order to send a letter

It shows why the speaker is going there.

In everyday Romanian, people sometimes use just să for purpose too, but ca să makes the meaning especially clear.

After ca să, Romanian normally uses the subjunctive structure, not the infinitive.

The subjunctive is usually formed with:

• să
  • verb form

Here:

• să trimit = that I send / for me to send

So:

• ca să trimit = so that I can send / in order to send

Romanian uses the infinitive much less than English in this kind of sentence.

Yes. In ca să trimit, the verb is in the subjunctive construction.

For many verbs, the subjunctive form looks the same as the present tense form:

• eu trimit = I send
• să trimit = that I send / for me to send

What marks it as subjunctive is mainly să.

So in this sentence:

• trimit by itself could be present indicative
• să trimit is subjunctive

O scrisoare means a letter.

Here, o is the indefinite article for a feminine singular noun.

• scrisoare = letter
• o scrisoare = a letter

Compare:

• un băiat = a boy (masculine)
• o fată = a girl (feminine)

So scrisoare is feminine, which is why it takes o.

Yes, Romanian word order is fairly flexible, but this sentence uses a very natural order:

• Mâine = time
• merg = verb
• din nou = again
• la poștă = destination
• ca să trimit o scrisoare = purpose

A very literal structure is:

• Tomorrow I go again to the post office so that I send a letter

You could move parts around for emphasis, for example:

• Mâine merg la poștă din nou...
• La poștă merg mâine...

But the original sentence sounds neutral and natural.

Yes.

• Mâine merg din nou la poștă... = very natural, common, especially for a planned action
• Mâine voi merge din nou la poștă... = also correct, a bit more explicitly future

Both work. In everyday speech, Romanian often prefers the present tense with a future time expression like mâine.

Some important pronunciation points:

• â in mâine is a central Romanian vowel that has no exact English equivalent
• ă in poștă is the short neutral vowel, somewhat like the a in about
• ș is pronounced sh
• sc in scrisoare here sounds like skr, not sh

Rough guides:

• mâine ≈ MUH-ee-neh (very approximate)
• poștă ≈ POSH-tuh
• scrisoare ≈ skree-SWA-reh

Stress:

• MÂI-ne
• POȘ-tă
• scri-SOA-re

Because poștă is the destination/place, not the thing being acted on directly.

• merg la poștă = I go to the post office
• o scrisoare is the direct object of trimit because it is the thing being sent

So the sentence has:

• la poștă = location/destination
• o scrisoare = direct object

It is neutral and natural. It works well in everyday standard Romanian.

Nothing in it is especially formal or especially casual. It would sound normal in conversation as well as in writing.