1 Harry has cool and fast broom stick.It's Harry's broom stick.
2My friend give me rulers and said Is it your ruler , Lee?
It is my ruler so I said " Yes,It's mine".
3I gave money at her birthday.
Now the money is her's.
4My father has books.It's My father's book.
5My mother buied hiking shose.
Now It is her's shose
Nice job on your sentences Ben. You did a perfect job adding 's to the end of names to make them possessive, such as "Harry's broomstick" and "my father's book". Great job! I also like how you showed me you could answer your friend's question by saying "Yes, it's mine." That is very impressive!
Just remember that "his" and "hers" are similar to "mine", and don't need an apostrophe ( ' ). I noticed you wrote "her's" but all you needed to write was "hers".
Other corrections:
-shose= shoes
-past tense of buy=bought
-Harry has cool...= Harry has a cool....
-broom stick= broomstick
GREAT job! Keep up the good work, Ben!