Here are three sentences summarizing the key points of the lesson in my own words:
1) Etymology is the study of the origins and history of words, including when they entered the language, their root sources, and how their meanings have changed over time.
2) Understanding word roots is important for determining a word's basic meaning, as roots generally come from Latin or Greek and carry the core definition that can't be broken down further.
3) The English language is constantly evolving with new words being added and existing words taking on new meanings, so learning etymology provides context about where words came from and how their usages have developed.