Hello Natishka,
Thank you for using Apple Support Communities.
It appears that you are getting extra characters being entered in your documents. Since you are getting them when you create a new Pages document, I would suggest that you next create a new user account on your Mac and try it there. The following article describes this testing process - - How to test an issue in another user account on your Mac.
You can also try testing the issue in safe mode. Here is an article describing that - Try safe mode if your Mac doesn't finish starting up.
Come back and let us know if the same thing is occurring in the new user and/or in safe mode. This will let us know where we need to go next to resolve this.
Best regards.