Kind of. They are someone who reads your chapters for you and looks for spelling and grammar mistakes that you missed and comes up with ways for you to better tell your story and just in general helps you with feedback like pointing out plot holes.
I have always been my own beta, rereading my chapters after posting them but it is much easier when there is another person there who doesn't know how you have the story planned out in your head and can bring their perspective to the story and chapter. It really helps with fixing plot holes and making the story more clear.
It is exactly what I needed so I am very happy about this and it is not only making my stories on the site better, but making me a better writer overall.