Answer :
Bills passed by Congress but vetoed by the President:
When the Congress passes a bill and if the President considers it as unnecessary or unwise and does not sign it; the bill gets vetoed that is the bill does not become a law.
And if there are majority of objections in the Senate house to the veto of the president, a vote is taken to overrule, or override, the veto. If the House do not vote on veto overrule, the bill gets stalled and it will not become a law.
Declared under the Constitution, Veto is a procedure by which the President of the nation refuses to sign a bill and thus preventing its enactment into becoming a law. A regular veto appears when the president returns the unaccepted bill to Congress for further procedures.