Today’s レッスン is an easy one.
レッスン is the transliteration of “lesson” in English.
When we use レッスン in katakana, that implies some kind of unofficial, private lessons, such as piano lessons or dance lessons.
A lesson is conducted in a school, it is not usually called レッスン but 授業（じゅぎょう）.
If I’ve learned a lesson from an experience that is called 教訓（きょうくん）.
Katakana is easy to learn but mastering katakana words may not be as easy.
For more beginners’ study material, please visit JLPT N5 Grammar and JLPT N5 Kanji pages.