If you have perfect vision, on a totally dark night and you viewed the Northern and Southern hemispheres simultaneously you would see approximately 9000 stars.
A decent home telescope would allow you to see 15 million stars.
The milky way contains approximately 400 billion stars
There are an estimated 170 billion galaxies in the observable universe.
Therefore it is estimated that there are more than 1,000,000,000,000,000,000,000,000 stars...