Plunkitt often talks about seeing opportunities and taking them. What does this mean?

That line was written by George W. Plunkitt (The former Senator of New York)  in his book.

When he said that line, he was referring to the time when he know that the government is planning to make improvements in his city. At that time , the government was planning to built a lot of infrastructure that will most likely attract more investment to the city.

Plunkitt saw this as a huge opportunity. So, Plunkitt decided to buy several lands on a cheaper price while speculating that the value will most likely increase in the future,.