Yes, it's roman.
But not from the 3rd century, 4th century instead. Constantinian or Valentinian period.
I can see the top part of a Victory to left holding a wreath, but everything else at the reverse is totally worn out.
On the obverse, I see a silhouette and two letters, nothing more.
I have a small idea of what it could be, but that's just an assumption from my experience and the coins listed in my collection.
Valens, SECVRITAS REIPVBLICAE, like this one I own: N#136381 , which I'm linking solely to illustrate my thinking.
I have to say that this coin is so worn that I think it can't be fully identified.
But, for only 25 reais ($5), it's fine, specially for beginners.