The apparent brightness of a star is called the magnitude (m). The lower the magnitude, the brighter the star. In general, stars with a magnitude of up to 6 are clearly visible to the human eye. The visibility of the star depends on the light influence outside.
If you live in a big city, there is immense light pollution from shops, lanterns, advertising, etc., which means that you can only see brighter stars with a small magnitude. But if you live in a village or drive out into the country, you have a perfect view of the night sky, including "darker" stars with a high magnitude.