Verific raportul încă o dată ca să nu fac o greșeală.

Because Romanian usually puts the definite article at the end of the noun instead of using a separate word like English the.

• raport = report / a report
• raportul = the report

So Verific raportul means I am checking the report.

In this sentence, încă o dată means one more time or again.

Literally:

• încă = still / yet / another
• o dată = one time

Together, încă o dată is a very common expression meaning again or once more.

Because here it literally means one time:

• o = one / a (feminine form)
• dată = time / occasion

So încă o dată is written as two words.

This is different from odată written as one word, which can mean things like once or formerly, depending on context. In your sentence, the separate form o dată is the correct one.

Ca să introduces a purpose clause. It means so that or in order to.

So:

• Verific raportul încă o dată = I check the report one more time
• ca să nu fac o greșeală = so that I don't make a mistake

Romanian can also sometimes use just să for purpose, but ca să makes the purpose relationship especially clear and is very common in everyday speech.

After ca să, Romanian uses the subjunctive, marked by să.

The verb here is a face = to do / to make.

For eu in the present subjunctive:

• să fac = that I do / make

This happens to look exactly like the present indicative:

• fac = I do / I make

So the subjunctive is shown mainly by să, not by a different ending in this person.

In Romanian, nu normally goes directly before the verb to make it negative.

So:

• fac = I make
• nu fac = I do not make / I don't make

That is why you get ca să nu fac o greșeală = so that I don't make a mistake.

Because the sentence means a mistake, not the mistake.

• greșeală = mistake (indefinite, basic form)
• o greșeală = a mistake
• greșeala = the mistake

Here the speaker wants to avoid making any mistake / a mistake, so the indefinite form is natural: o greșeală.

Yes. That is a very natural alternative.

• a face o greșeală = to make a mistake
• a greși = to make a mistake / to be wrong

So these are both possible:

• Verific raportul încă o dată ca să nu fac o greșeală.
• Verific raportul încă o dată ca să nu greșesc.

The first is a bit more literal, like make a mistake. The second is more direct: so that I don't make a mistake / so that I'm not wrong.

Romanian present tense often covers both ideas, depending on context.

So Verific can mean:

• I check
• I am checking

In this sentence, English would usually translate it as I’m checking the report one more time... because it sounds like a current action with a purpose. But grammatically, Romanian just uses the present verific.

Not completely. Romanian word order is fairly flexible, though some versions sound more natural than others depending on what you want to emphasize.

Your sentence:

• Verific raportul încă o dată ca să nu fac o greșeală.

A possible alternative:

• Verific încă o dată raportul ca să nu fac o greșeală.

Both are understandable. The original version puts raportul earlier, so the object is introduced right after the verb. The alternative gives a little more emphasis to încă o dată.

They are doing two different jobs, even though the form is the same.

In o dată:

• o means one
• so o dată = one time

In o greșeală:

• o is the feminine form of the indefinite article, like English a
• so o greșeală = a mistake

Romanian uses the same form o for feminine one and feminine a, so context tells you which meaning is intended.

Yes, but the structure would change slightly.

You could say:

• Verific raportul încă o dată pentru a nu face o greșeală.

This also means I’m checking the report one more time in order not to make a mistake.

Difference in tone:

• ca să = very common and conversational
• pentru a = a bit more formal or written

Both are correct.