This phrase is often used when discussing changes of roles, especially in jobs or positions of responsibility. She'll be stepping into his shoes as the new CEO next month.
Pro Tip 2/3
Sense of Responsibility
Implies adopting not just the tasks, but also the expectations and pressures the previous person faced. Taking over as team leader means you step into her shoes, pressures and all.
Pro Tip 3/3
Immediacy
The phrase often suggests the need to quickly adapt to the new role without much preparation. Due to his sudden departure, I had to step into his shoes immediately.