This is only a written short form of association — a group of people who join together for a shared job, sport, or cause. You meet it in names on letterheads, websites, and name badges: the Parent–Teacher Assoc., the Taiwan Medical Assoc. People almost never say the clipped form out loud; they still say the full word association when they talk. It sits in the same family of paper shortcuts as Ltd. or Inc.: useful on a sign, odd in speech. Though actually, in older British writing Assoc. can also stand for Associate as a title before a name. In school and on forms here, it nearly always means the group, not the job title. If you see it after a long official name, read it as association and you will be right.