This message is due to the Plesk SSL Certificate being linked to the Control Panel, so since your hostname/domain is not 'Plesk', Apache is warning you that the SSL Certificate name does not match.
This is not a critical error or warning, it can be ignored, or you can get your own SSL for your hosting domain and change it to your certificate, then these messages should stop.
You can either purchase a real Certificate, or generate your own 'Self Signed' one (which is free).