It is an English expression for "web payments", "use the internet to make bank payments, services or goods". In Latin America it appears in advertisements, because in English it looks cooler.
WEBPAY (and not WEB PAY) is a company that provides the service of payment of bills and online purchases, through the internet. It can be a contracted and paid or free service depending on the commercial area in question. The name is a contraction of web pay or payment over the network.