Answer:
This quote is basically saying that the most important thing you will ever learn in life or throughout your life is to give out love. weather that being giving someone your spot on a bus, it's not just an act of kindness but it is love. you are showing someone you care, and to let love come in. this basically means to let other people love you in life.
Now I don't particularly agree with this quote but it is important to give love out and to let love come back to you.