In the solution for b why is there switch 2?

i need to know!!

I think that's how you properly rotate the molecule so that H is in the back. The way I would do the problem is, assign priority numbers to the groups like they did. Then, if the lowest priority group isn't in the back, ie doesnt have dashed lines, then you switch the configuration. So, in this problem, when you first assign numbers, it's supposed to be R, but H is a solid line, so switch to S.