This quote means that when you do something kind or meaningful, you can share the positivity with many people, and you won’t be any worse off for it. In other words, happiness is infinite and can always be shared and spread to others, no matter how much kindness or joy you are sharing. The idea is that everyone can benefit from your kind act and the act itself will not take away from your own happiness. Imagine a single candle providing light to a thousand people. Sharing the light in no way decreases the amount of light the candle originally had. In the same way, when you share your happiness it does not get any less.