Open protocols are protocols that have open specifications that can be implemented by anyone; HTTP is one such protocol. (If what you quote is taken directly from that article, then that article is not correct; SOAP is not the only way to create web services.)
SOAP is an XML dialect used for implementing web services. It *can* be transported over HTTP, but there are other mechanisms as well, although they are much less commonly used than HTTP. For more information see
SOAP.
Note that SOAP is just one way to implement web services, and no longer the most popular one - RESTful web services have become very popular in the last few years.
*Web* services generally use HTTP, that makes them *web* services. It's possible to write services using other transport protocols, though: raw TCP, SMTP, messaging, ...