here is how Wikipedia describes it:
Ethiopia and Eritrea[edit]
Main article: Naming conventions in Ethiopia and Eritrea
Ethiopians and Eritreans have no concept of family name and surname. If one is to refer to a person, it’s with a single name and they will always use the person’s given name. Ethiopians and Eritreans use a naming pattern very similar to the Arab naming pattern, but with one exception: no suffix or prefix. The full name of a person is usually two but officially registered with three names. The person’s given name comes first, followed by the person’s father’s given name and (optionally, for official purposes) the grandfather’s name at last. For example, a person named Lemlem Mengesha Abraha has Lemlem as her given name, Mengesha (from her father’s name) Abraha (grandfather’s name). The grandfather’s name is usually only added in official documents and not used in everyday life. The father’s name is not considered a middle name but a last name, without it being a family or surname. The same is true for women; they do not take their husband’s last name. They go independently by their given name, followed by their father’s name, and then their grandfather’s name, even after marriage. In both Ethiopia and Eritrea, a person is always addressed by his first name; for example Mrs. Lemlem or Dr. Lemlem.