Why you can put here "il est"? isn't it the rule that before an article you must write c'est?
I don't know if it's a rule but that sentence is weird for me. In English it's ok, you can say that like this but it would translate:
"Il est comme mon frère"
For me Il est comme mon frère. is He is like my brother.
And the Duo French sentence is wrong IMO: C'est le même que mon frère. is the correct way to say it.