Very simple, you just need to type \n[x] where x
is the ID of your hero. If you are renaming the first hero in the database, you just need to type \n in the message in Show Text.
Let's say you want him to say "Hey there, Mike!"
Type "Hey there, \n!"
And when you play the game, the man will say "Hey there, Mike!", replacing the \n with whatever name the player renamed Mike.
Also next time please use the in-built RMVX Help topics.
Have a nice day and Happy New Year in advance