As Mark notes, searching the Internet you'll find tons of information on MPLS.
Basically the underlying technology adds a tag to L3 packets, much as VLANs add a tag to L2 frames. Originally the tag was added to L3 packets to allow high speed switching of the packets vs. slow speed (at that time) routing of packets. Today, MPLS is probably of more interest for what it supports "virtually"; the latter often being of special interest to service providers (much as Q-in-Q L2 is too).
When you write to "know how to deploy it", do you have something in particular in mind?
