Let's write some barnyard humor:
We wrote a short script to deliver the joke using the say block to display speech bubbles. After three seconds of silence, our horse tossed out a comedic cliché, "Is this thing on?"
We introduced two variations of the say block. For the joke and punchline, the horse spoke for a specified number of seconds. However, at the end of the script, the say block we added did not specify a time value. And if you look at the stage, you'll notice that the speech bubble still displays Is this thing on?.
If we want the action in our script to continue while the speech bubble displays, we use the say block without a time value. For example, we could make a sprite speak while moving across the stage.
If we use the say block with a time input, the speech bubble displays for the time specified. However, the next block in the script does not execute until the time elapses. This gives us a way to synchronize our scripts.