Intentional online sellers and ecommerce websites need online seller accounts and virtual bank accounts to collect funds from marketplaces such as Amazon, ebay, they also need these accounts to connect to different credit card processors such as Stripe and Braintree.

The term "online seller account" is a pure marketing ploy to target online ecommerce merchants. the product is exactly the same as most virtual bank account solutions provided by the likes of B2BPay, Payoneer or World first.

A definition from Icomparefx.com

"An international online seller account facilitates collection of electronic payments through different online marketplaces. These accounts essentially work as payment gateways, giving small and mid-sized businesses the ability to process credit and debit card payments without opening merchant accounts with banks. Other than providing access to receiving accounts in different countries and currencies, some of these accounts also let you make payments to international suppliers."