Jr. is a small written tag after a man's name, meaning he has the same full name as his father. Thomas Bell Sr. is the father; Thomas Bell Jr. is the son. It is not a job, not a school year, and not a size of clothes. You see it most in American names, on letters, forms, and news. Daughters almost never get Jr. When the father dies, some sons drop Jr.; many keep it for life because that is how their bank papers and school papers are written. Though actually, junior as a normal English word also means “younger” or “lower in rank” — a junior doctor, junior year — and that is not what this Jr. after a name is doing. Here it only marks the son with the father's name.