The second in order or rank; refers to the person or thing in the number-two position (commonly used as 'the second ~').
彼はチームで二番目に背が高い選手だ。
He is the second-tallest player on the team.
二番目の問題を解いてください。
Please solve the second question.
妹は家で二番目の子どもです。
My younger sister is the second child in the family.
優先順位の二番目には費用削減が入る。
Cost reduction comes in second place on the priority list.