Hello YYC132,
Welcome to the Community. Glad to learn you're using QuickBooks to help record time against a customer. I'll be happy to guide you in the right direction so you can get back to doing what you enjoy.
The "activity" in question is refers to the activity associated with the time you're entering. For example, a tailor shop may have a time activity for an employee called "sewing". This activity is entered to show that the time being entered was spent on sewing. You're welcome to ask other questions or leave questions in the comments below.
I'll be a message away. Otherwise, I wish you a great rest of the day!
