The man with the backpack put down his plastic sack and walked over to give the man in the chair a coin or two for tzedaka. Tzedaka commonly refers to charity, but its actual meaning is "justice" or "righteousness".
How is it you giving your money to a poor person is called justice? Okay, so it is righteousness. You giving something of yours to someone else just because he needs it is a righteous act, but how is it justice?
The fact is those coins you generously give away are not really yours. At least 10% of the money in your pocket was never intended for you. Hashem gives us our income with the instructions that poor people are to share in it, too.
What is so interesting about this man giving tzedaka is that plastic sack he put down is filled with empty, plastic bottles. To encourage recycling the government insists that the price of drinks sold in plastic bottles be increased by 35 agorot (approximately 10 cents) so poor, or very thrifty people will go from garbage site to garbage site searching for plastic bottles to turn in for coins. Here we see someone who obviously counts every coin he manages to find, but still he is particular to give those who are even more needy their share of what he finds, too.