one of the stages or levels in something such as a process or organization, through which it is possible to rise or make progress

I started my life on the bottom rung of the ladder in this company. 我从这个公司的最基层干起，开始了我的职业生涯。

For her this was just the first rung on her career/professional ladder. 对她而言这不过是她职业生涯的第一步。

Once you rise a few rungs up the ladder, life becomes easier. 一旦你上升了几个层次，你的日子就会好一些。