Dear EdziuMM
It looks very much like #1091;#1087;#1091;#1090;#1085;#1080;#1094;#1072; to me. Not that I can write or read Serbian. But what I have discovered by typing out the individual Cyrillic letters is that it may not be a place but the word postal order (see also
https://www.posta.rs/cir/stanovnist...ka-uputnica).
Best regards from Switzerland
André
Edit:
Sorry: In the preview the Cyrillic letters were visible, after posting there are only funny numbers...