If something is printable, it is clean enough to put on a page that anyone might read — a newspaper, a school magazine, a public notice. No rude words, no ugly jokes. People often use it in the negative: hardly printable means almost too rude to print. That is the sense you meet in stories and news, and it is a polite way of saying the language is too rough to show. Though actually, in computer talk the same word also means “a printer can print this” — a printable file, printable characters (the letters you can see, not hidden codes). Same spelling, two jobs: one about manners, one about machines. This entry is the manners one.