Question

how many stars and stripes does he American national flag have?

Answer 1

there are 13 stripes and fifty stars 

Answer 2

если нужен ответ на поставленный вопрос, то:
The American national flag has fifty stars and thirteen stripes.

хотя и ответ будет правильным:
There arу fifty stars and thirteen stripes on thу American national flag.