It is / he is
C'est un enfant.<pre>
1He is a man. 2He is a boy. 3He is a child. Doesn't this translate to IT's a child ? He is a child should be "Il est un enfant", right ?</pre>
"it" generally does not refer to a human being. the French sentence mentions "un enfant", meaning the child is a boy. therefore, the more faithful translation should be "he is a child".
C'est can "this is", "that is" or "it is". In French, you say "c'est un homme", ou "c'est une femme", but if you modify with an adjective, you need to say "il est un bon homme", ou "elle est une jolie fille." It's actually more complicated than that, though! See the following link for details: http://french.about.com/library/weekly/aa032500.htm
Thank you, that rule does explain why it doesn't translate to "it's a child" , however, it does not teach how to i.e say that the child is a girl, how do you make that difference when the word enfant will alwas be masculine and preceded with "un" which to me is the only thing in this particular sentence explaining the sex of the child?