XML-RPC is a remote procedure call protocol which uses XML to encode its calls and HTTP as a transport mechanism.
In distributed computing, a remote procedure call is when a computer program causes a procedure to execute in another address space, which is coded as if it were a normal procedure call, without the programmer explicitly coding the details for the remote interaction.
In computing, Extensible Markup Language is a markup language that defines a set of rules for encoding documents in a format that is both human-readable and machine-readable.
The Hypertext Transfer Protocol is an application protocol for distributed, collaborative, and hypermedia information systems.
OpenERP 7 - Import data using XML-RPC and Python Script by OpenERPConsulting
"XML-RPC" also refers generically to the use of XML for remote procedure call, independently of the specific protocol.