The word savior means someone who saves a person or persons from something else, usually that which is harmful to them.  In the context of Christianity, Jesus is the Savior.  This means that he saves us from the righteous wrath of God the Father upon all who have sinned against him.

Sin is breaking the law of God (1 John 3:4).  The wages of sin is death (Rom. 6:23) and separation from God (Isaiah 59:2).  Therefore, Jesus is the Savior who saves us from eternal damnation.