Final answer:
To let the second customer know that you have their attention, you can make eye contact, smile, and say hello.
Step-by-step explanation:
To let the second customer know that you have their attention, you can use a combination of actions. First, make eye contact with them. Looking directly at the person shows that you are focused on them and ready to assist. Second, smile at the customer. A warm and friendly smile can help them feel welcomed and acknowledged. Lastly, you can also verbally greet the customer by saying hello or offering a polite greeting, further confirming that you have their attention.