Hello, Its virus? Every day it appears on my calendar

no, it's just spam

read

How to remove Calendar spam? - Apple Community

maybe you allowed a website a subscription (don't know if this word is right, I`m german) so that it is allowed to write anything in your calendar. if you click on "calendar" (if you're in the app calendar its at the bottom, there might be 3 words, its the middle one, I think) you can disable it by easily clicking on it.

if this doesn't work, I don't know what else you can do

or just do it like Rudegar said...