Great! You just printed something to standard output.

You may have noticed that there is a newline character at the end of your message. The say function adds the newline for you, comparable to Ruby's puts or Java's println.

If you're coming from Perl5, print may be more familiar to you and works the same in Perl6.
print "Hello World!\n"

Try printing something without the newline:
print "Hello World!"

You'll notice the web REPL displays a dot next to the string. Don't worry you didn't print the dot, the web REPL added this to indicate that there is no newline at the end of the string.