Google Apps Script is a JavaScript cloud scripting language that can be used to automate tasks and extend Google Workspace apps. It allows users to write scripts that integrate with and customize Google Docs, Sheets, Slides, Forms, and more. Some key capabilities include creating standalone scripts, spreadsheet/app-bound scripts, and site-bound scripts. Triggers can be used to run scripts on time-based events or user edits. The presentation provided examples of using Apps Script to automatically grade quizzes and perform mail merges. Resources for learning Apps Script include documentation, tutorials, videos, and Stack Overflow.