Website redirects when accessed from Google

Hello, I have a website and it redirects to strange pages when it is accessed from google. I logged in the FTP, and there are tens or hundreds of files and folders that should not be there.
Does anyone know how to fix this issue and how it appeared?
Here is an image with the files: https://s15.postimg.org/cjyqtuirf/files.jpg
Thank you!