In many English-speaking schools, the PTA is a group of parents and teachers who work together for that one school — raising money, helping at events, and talking with the school about what children need. It is a school-community group, not the school office and not the government. The letters are usually said one by one: P-T-A. In the US and UK the name is very common. Though actually, Taiwan schools already have something close, often called 家長會; that is not always the same kind of volunteer club, so when people here say PTA they often mean the English-speaking-school kind, or they are borrowing the English letters as a handy name.