What is AGILE

It means continous iteration of development and testing throughout Software Development Life Cycle(SDLC) of project. Here iterative approach is choosen and software build is delivered after each iteration.The customer is able to see the result after each iteration and tell his comments.

It is not developed as a complete product at the very first time itself.
Each iteration has some features and at the end of final iteration and upon the approval of customer , the product is finalised and go for deployment.

This is one of the advantages of agile development.The disadvantage is that requirements are not freezed before.Hence it is difficult to estimate the resources and development cost.
The final build has all features required for the project.
What is Sprint?
Agile iterations are known as sprints.
Each sprints lasts for 2 to 4 weeks.But mostly 2 weeks.
At the end of each sprint the product is delivered to the customer and wait for feedback.
If the customer has feedback ,it will be included in next sprint.