Point Spread Explained NHL Point Spread Bet Confusion. Please Explain For Me.?

NHL Point Spread bet confusion. Please Explain for me.? - point spread explained

I bet for a margin of one point:
PII BUF - Buf win (-0.5)
CBS at DET - Det win (-1.5)
Chi to win NSV - NSV (-1.5)
To win in LA VCR - Video recorder (-1.5)
-1.5 And -0.5 What does this mean? How to win by 0.5 points? Please explain.