"Management of opportunity" means looking for chances to do something good and then making a plan to make sure you take advantage of that chance.
Imagine you're walking down the street and you notice that there's a person who needs help carrying their groceries. You might have an opportunity to be kind and help them out. So, you decide to manage that opportunity by walking over and offering to carry their groceries for them.
In other situations, you might have an opportunity to learn something new or to take a new job. To manage these opportunities, you might make a plan to research the job or sign up for a class to learn more.
The key to managing opportunities is to pay attention to what's happening around you, think about what you want to achieve, and then make a plan to take advantage of any chances that can help you get there.