I´ll guess that this symbol is too prevent bad words from being written but on other languages some random words are being censored. I wrote "Atenção" (Attention in Portuguese) on a sign  and it was censured for no reason. This bug doesn´t happen all the time. Sometimes the word is censored and sometimes it doesn´t. I typed "Atenção" in one sign and nothing happened but on a sign next to it it was censored.