1) The word "flower" contains two vowels: O and E.

2) Angelina Jolie is an American actress, filmmaker, and humanitarian. She has received critical acclaim for her performances in films such as "Girl, Interrupted," "Mr. & Mrs. Smith," and "Maleficent," and has been actively involved in humanitarian work around the world.

3) The word "banana" contains three vowels: A, A, and A.

4) Serena Williams, an American tennis player, has won a total of 23 Grand Slam singles titles, making her one of the most successful players in the history of the sport.