A girlsbar in Japan is also known as Hostess bar for one on one attention, in which a girl will sit beside a customer to chat with them and share drinks.
Although it's important to note that the interactions between the customer and the girl at the girls bar does not include any sexual advances or physical advances.
Basically the girls at the girls bar in Japan talks to the guys, sings for the guys and ensures the guy has a good time, but with no sexual contact.
A hostess club in Japan is essentially a type of night club that is found primarily in Japan which employs mostly female staff and caters to men seeking drinks and attentive conversation.
Host clubs are a similar type of establishment where mostly male staff attend to women.
And unlike hostess clubs in which the customers sit at tables with hostesses, girls bars on the other hand usually have a counter where the customers sit and converse with the bartenders.
This setup creates a more casual and relaxed atmosphere.
When you enter restaurants and shops in Japan, you will hear all the staff say "irasshaimase" to say hello to the customer.
Don't be afraid, the staff don't wait for any reply, but you can say thank you with a nod and a smile.