A bachelorette party is a party that a group of people (usually women) throw for someone who is about to get married. This person is called the bride-to-be.
Think of it as a special celebration for the bride-to-be and a fun way for her to say goodbye to her single life before she gets married.
The party can be held in many different places and can involve many different activities. Some common activities include going out to eat at a fancy restaurant, going to a spa, or having a sleepover with games, movies, and lots of snacks.
The people who are invited to the party usually include the bride-to-be's close friends and family members. They might give her gifts, play games with her, or make her wear silly clothes or accessories.
Overall, it's just a fun time for everyone to celebrate the upcoming wedding and show the bride-to-be how much they care about her.