Evil eye is a negative force or energy produced by destructive feelings like envy , jealousy , anger etc. These feelings make people wish negative thoughts which are transformed to other people by the look in the eye. Eyes are the reflection of the soul and the negative force passing through it make strong influence on the soul.
Hamsa hand symbol is an ancient Jewish and Muslim amulet talisman which is believed to protect person from this destructive energy. Naturally all the constructive and positive energy is protected and not wasted on fighting the evil eye energy. The person's energy balance remains positive , which brings him more luck , health , happiness , love