“Staff Engineer” is about halfway up the technical career ladder in many places, with a few possible (but increasingly rare) levels above, and a few levels below. Someone promoted to staff engineer likely has at least 5 years of work experience (probably more) and is self-motivated, good at their job, gets along well with their coworkers, and has some technical vision.

Many of these people might have some quasi-managerial duties (interacting with other parts of the organization, helping with recruiting, ...), get roped into more meetings than they would like, or make high-level technical decisions and delegate work to a handful of more junior engineers, but most of them are sitting at their desks writing code a significant part of the day (or perhaps rewriting the schlocky code that the junior engineers just handed in).