There's more...

If you put your cursor over the output on the right-hand side, you will see two buttons: one that looks like an eye and another that is a rounded square:

Click on the eye button to get a Quick Look box of the output. This isn't that useful for just a string, but can be useful for more visual output, such as colors and views:

Click on the square button, and a box will be added in-line, under your code, showing the output of the code. This can be really useful if you want to see how the output changes as you change the code: