What is the functionality of Send Link and Pay Now buttons in Payments?

You will find the Send Link and Pay Now options under the More button of a payment record.
Here is an explanation of both of their functionality:

• Send Link - You can send the payment gateway link to the customer to make the payment. 
• Pay Now - You can manually enter the customer's credit card or bank details and make the payment. 

To learn more about Payments, click here.