Use the zero article when making generalizations:
I love chocolate
these are oranges, not apples
waitress!
happy birthday
men are bold
words of kindness are always appreciated
she has measles
he is battling cancer
Use the zero article with a non-count subject:
money is important
greed is good
beauty is timeless
Use the zero article with names of sports, or academic subjects:
baseball, football
mathematics, geography, physical education, computer science