"I am not a man."
Translation:Eu nu sunt un bărbat.
You can add the Romanian layout in your settings. Usually, there is a key somewhere near the space bar (a globe icon or a gear icon) that brings you right to the language settings where you can choose the layouts (and if you have more than one installed, you can switch between layouts via that key). But since it's slightly different from device to device, you might have to look up the exact process for the device you own.
I think it is more common not to use it. When you say "Eu nu sunt un bărbat", you are negating the indefinite article "un". That sentence could be followed by "Eu sunt cel mai important bărbat" " I am the most important man". So what you do here is counter the anonymity of the indefinite article.
If you want to negate the noun, you do not use the indefinite article.
After the political changes of 1989 in Romania, at some point in the 90's some orthographical reforms were introduced. One of them was to "revert" the writing of "sînt" to an older form of "sunt". I would not go into detail why and I disagree with all the changes introduced (although I follow them because there needs to be a standard), the idea is that in this particular case the pronunciation is exactly the same, because it is exactly the same word, just written differently (as a side note, an even older writing form was "sûnt" (again, with the same pronunciation as "sînt")).