While it's not always exclusive to hairdressers, it's strongly associated with them. The barber pole's origins go back to the time when barbers also performed surgery and bloodletting. The red and white stripes represent blood and bandages.
Nowadays, the barber pole often signifies a traditional barbershop offering haircuts, shaves, and other grooming services. However, some hair salons might also display a barber pole as a decorative element, particularly if they offer men's haircuts or traditional barbering services.