This is the 639th most frequent Japanese word.
当選
Winning (e.g., a prize or election).
In this sentence, '当選' refers to winning an election, specifically being elected through public voting.
彼は市長選挙で当選しました。
He was elected in the mayoral election.
In this instance, '当選' is metaphorically used to describe aiming to achieve a successful result, such as passing an exam or being accepted.
志望校受験に当選できるように頑張ります。
I will work hard to get accepted into my desired school.
Here, '当選' is used to express winning a prize or lottery, meaning being selected in a random or specific draw.