This article only concerns such citizens that are not eligible for visa waiver! If you need a visa to enter Germany, then you are not eligible for visa waiver period!
What is an entry visa?
This is a national visa with the one and only purpose to give you the right to enter Germany and finish your application for a residence permit.
Huh? What do you mean finish the application?
Well, German bureacracy does have its logic. This visa is exclusively the permission to enter Germany but not the permission to live in Germany. The next steps will be to find / move into your place of living and register it at the registration office, make an appointment with the immigration office of your city and apply for / pick up the residence permit. If you fail to do so yourself, your immigration lawyer or relocator will help you.