A script is a written version of a play or movie. If you're auditioning for a movie, you'll get the script to practice a scene or two.
Script comes from the Latin scrībĕre, meaning "to write," and all its meanings have to do with something written. Your handwriting is your script. The written version of what you're supposed to say, whether for a wedding toast or a play, is a script. And if you were feeling old-fashioned you could call the grocery list you just wrote a script. It's also a verb. You can script a play.