To capitalize is to put something in capital letters, particularly the first letters, Like This. To capitalize also means to take advantage of a situation.
The first word of every sentence is capitalized, and to capitalize is to write in capital (or upper-case) letters. To capitalize also means to take advantage of an opportunity. Graduates try to capitalize on their degrees by getting well-paying jobs. A football team tries to capitalize on the other team’s mistakes, such as making a touchdown after an interception. It might help you to remember that capitalizing is a good thing if you know capital is also another word for money.