What year were you born?
What year did your kid enter college?
How many years did the American Civil War last?
You have the kanji what and year, as in: "what year is it?"
This also means how many years too, depending on the context. As in: "How many years did you play soccer?"
The readings are both the readings you learned with the separate kanji, meaning you should know them. How many years have you been studying kanji now? You should be able to read this one.