It references the book Lean In by Sheryl Sandberg, the COO of Facebook. The book has been incredibly popular (at least here in the US), and has also received a fair amount of criticism. Sandberg addresses the fact that most high-level positions in companies are still held by men. Women have more opportunities outside the home than they did 50 years ago, but they still face many obstacles in juggling their professional and personal lives. I think her argument is that many women focus on starting families during their childbearing years and become less driven to excel in the workplace. Success isn't out of their reach, but women need to "lean in," that is, they need to purse professional success with the same drive and focus as their male counterparts. One of the main criticisms is that Sandberg is an upper-middle class white woman with resources and opportunities that many women don't have access to. It's easy to say that women can have families and high-profile careers when you have the money to hire a nanny and a comfortable financial safety net. Also, not all women are wives and mothers, so what about them?