Also, what exactly is a walkout protest?
Exactly what it sounds like.
Protesting by walking out of the place you're supposed to be.
Could be at a school, where all the students (and/or teachers) just walk out.
Could be at an office, where all the employees just walk out.
It's protesting by not working, but is more visual, because everyone was actually there and then walked out, rather than not turning up, or congregating elsewhere.