An algorithm is greedy if it builds up a solution is small steps, choosing a decision at each step myopically to optimize some underlying criterion. In other words, a greedy algorithm chooses the optimal solution locally, in hopes of achieving optimization globally. In many cases, a greedy algorithm does lead to an optimal solution, however there are times when this breaks down (i.e. the postage stamp problem from the lecture slides).
This section is definitely a 10. Super easy to read and understand!