What is capital? Please help?

Capital in that statement is just money. Whenever you build a system like that you need money upfront as an investment into getting it done. There are permits to buy, people to hire, supplies need to be purchased and this requires upfront money which can come from investors into the project or a business loan from a bank or it can just come out of your own pocket if your rich enough to do it alone but capital in that instance = money.