Multiple variables in textView and XML declaration

I apologize beforehand if this is an easy question, however i am not able to find something relevant.

What i want to do:

Let's say i have a string: My name is -variable- and I am -variable- years old. I live -variable- bla bla bla.

How do i declare this on XML?

Any guidelines and directions for more reading regarding this topic are appreciated.

Thanks a lot and in advance