When a hurricane makes landfall, many watches and warnings can be issued throughout the duration of the storm. The general difference between watches and warnings are that watches mean conditions are favorable for dangerous weather to happen so they are "watching" for them; whereas warnings mean that conditions are happening now or soon and you should seek protection.
There are many watches and warnings that can occur during a hurricane. The storm can produce tornadoes and flooding rains, storm surge along the coast, and high winds along the coast and inland. Hurricane watches and warnings are defined below:

The more you know:
Hurricane and Tropical Storm watches and warnings are given by the National Hurricane Center. All other land-based watches are given by the Storm Prediction Center (Norman, OK) and the local National Weather Service gives all other warnings.
For active watches and warnings year around:
For more information, please visit:
USA Today Article - What watches and warnings mean