"वह उसे बताता है कि यह नामुमकिन है।"
अनुवाद:He tells her it is impossible.
'to' is not used with 'tell'. 'Tell' always take an object as it needs a speaker and a listener. It doesn't need 'to' to specify the the object. Look in this link, there is always something beside tell and no to is used. http://sentence.yourdictionary.com/tell . That's not in case of say