Server start-up Error

Hello there! My friend has recently started to make a server. When he tried to run it for the first time, he got an error code. The picture below is the error code. If you could be of any help and to tell me what this code means and what he can do to fix it... it would be much appreciated. Thank you so much.

~DaKid

i.imgur.com/IdoAC.png

^ For some reason, the image will not come up. Just copy and paste that into a new field. Thank you.