Hi Tanu,
SOA means a change in the perspective how the enterprise looks at their IT solutions. Instead of creating isolated applications they think in reusable services. Once a solution is needed it can be modeled as a business process and can be composed from existing and/or new services.
(For sure there are many other ways to describe it.)
Here is one IBM article about this topic
http://www.ibm.com/developerworks/webservices/library/ws-soa-design/
Tamas