If the president vetoes a bill, it can still become law if congress overrides the president's veto with a majority.

If the president vetoes a bill, it can still become law if congress override the president veto with A TWO-THIRD majority.
If a president refuses to sign a bill into law, the congress men can still manage to pass that bill into law, if 2/3 of them can vote in favor of the bill. That is, to pass a bill into law despite the president's objection, then it requires a two-third vote from each of the chamber.