A vocab lesson is a lesson that focuses exclusively on a list of words and/or phrases, which are taught through a specific series of activities. This vocabulary is often related to a particular topic (such as "Animals" or "Common Foods"), a particular part of speech (such as "Adjectives" or "Verbs"), or a particular learning assignment (such as the chapter vocabulary lists that instructors will sometimes make for students).
Vocab lessons do not contain reading passages, videos, or other content beyond the vocabulary list itself.