Most of the time, the governor has three days to sign a bill or to veto it. If the governor takes no action within three days of presentment, the bill will become law.
However, the timeline is different for bills passed in the last three days of a session. The governor has 14 days after the adjournment of the legislature to sign or veto a bill. If the governor takes no action within these 14 days, the bill will not become law. This is known as a pocket veto.
For a more detailed description of vetoes, please see The Veto Process and Powers of the Governor.