A SWIFT Code (Society for Worldwide Interbank Financial Telecommunication) is required when a person wants to remit money from his account to another account which is present in a different country. For a example, if a NRI (Non resident Indian) wishes to remit money to say his family members SBI Bank account in India, he would need the Swift code of the branch in India in which the account exists.
It has to be noted that not all branches are SWIFT enabled. If this is the case, the person remitting the amount to India may choose the nearest branch (by location) that is SWIFT enabled so that the branch then transfers the money to the account that it should be transferred to.
It normally takes 1 to 3 days for the money to show up in the creditors account.
To see the list of SWIFT enabled SBI Branches in India and their corresponding SWIFT codes, please see this.
Alternatively, you can also use services like Paypal to transfer money to persons in India.