1. A stepping stone is a stage leading to another one in one's career or life goals.
a stepping stone to my dream job
'A stepping stone' is used to refer to a stage in one's life or career that leads to another more desired one. Some people talk about 'climbing the ladder' or 'moving up the ladder' in their career, and so this expression, 'a stepping stone' fits nicely. Each step you take is a move towards your ultimate goal.