En ole varma, onko tämä oikein.

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Breakdown of En ole varma, onko tämä oikein.

• olla: to be
• tämä: this
• ei: not

Questions & Answers about En ole varma, onko tämä oikein.

Why is it En ole varma and not something like Olen ei varma or Ei ole varma?

Finnish forms negation differently from English.

• En is the negative verb in the 1st person singular (I):
  
  • en = I do not
  • et = you do not
  • ei = he/she/it does not
  • emme = we do not, etc.
• ole is the basic (present tense) form of olla (to be) when used with the negative verb.
• varma is the adjective sure.

So the structure is:

• en (I do not) + ole (be) + varma (sure)
  → En ole varma = I am not sure

You cannot say Olen ei varma, because Finnish does not use ei as a separate word after a normal verb; the negation must be the finite verb itself (en).
You also cannot just say Ei ole varma if you mean I am not sure, because ei would be 3rd person (he/she/it), not 1st person.

What exactly does En ole varma, onko tämä oikein mean? Is it the same as I am not sure if this is correct?

Yes, that is the natural English equivalent.

• En ole varma = I’m not sure
• onko tämä oikein = if / whether this is correct/right

So the whole sentence is:

• En ole varma, onko tämä oikein.
  → I’m not sure if this is correct.
  (also: I’m not sure whether this is right.)

The nuance is the same: you express uncertainty about the correctness of tämä (this thing).