First let's describe what is social capital. Social capital means giving value to human relations, human connections, and networking. Rather than saying that the human side of a business-minded world is not important enough, social capital gives back the power to multicultural tolerance, friendship, social networking, and the inherent need to make meaningful connections.
And it is important: the more tolerant, friendly, understanding, patient, and communicative we are, chances are that we will become a model to others and you will get the same amount of kindness from others. You get what you give, is the central premise of this philosophy: do onto others as you wish others do onto you.
In the context of global citizenship and multicultural understanding, social capital is imperative because our world is becoming flatter and flatter with the resources of technology. We no longer do business with one or two countries, but with whoever is out in the market willing to market, sell, buy, and extend aid and other things. The world is now being led by people from all walks of life: multiracial, special needs, tattooed professionals, people of different sexual orientation, people of other faith….that is what multicultural entails: all cultures and subcultures alike.
Moreover, multicultural understanding is about information: laws, ideas, politics, policies, jobs, news. All that information that comes from so many countries in so many ways affect our economy, our own politics, policies, jobs, news, and ultimately our ideas. Refusing to understand diversity and establish contact with all humans equally is the same as limiting yourself from a record number of opportunities. As you show your social capital, you demonstrate your persona as a "citizen of the world". A citizen of the world is a citizen that can take any challenges because they are ready to take on the world itself without fear of anyone who may be or act differently.
Additionally, when we show good will, and good faith in any and every aspect of life, you will find that the bond that you create is stronger than any want or will from others to do you harm. Many great leaders, because of their social capital, are untouchable because of how they inspire respect. It is behavior that elicits initiative, intelligence, culture, and also builds community.
Examples of social capital in multicultural understanding include making support groups (study groups, focus groups, business groups, support groups) with and for people who are different than us. Also, welcoming the opinions of others into decisions, considering the needs of others when creating policies are part of social capital.
Another example: you do not have to be homosexual, or straight, or a drug addict, or a priest, or a criminal, or an artist, or a doctor in order to support the rights of all of these individuals. Politicians who are truly invested in their work build policies and make laws to support, protect, and defend people even though they do not share the same culture as them: special needs populations, poor communities, high-risk populations, and even those who may not have issues but have wants and needs are equally protected. All of these people may be different, but they work together and for each other. That is the essence of social capital under multicultural understanding.