Welcome to the forum. People are very helpful here. It’s a great place to be if you have hearing problems, or suspect that you do.
If you spend time here, you’ll quickly learn the common terms. A web search for, say, “ite hearing aid” or “opn hearing aid” will tell you what they mean. “on hearing aid” won’t help so much. It’s an obsolete app from Oticon. By the way, neither OPN nor ON are abbreviations.