Answer:
glossary
Step-by-step explanation:
The glossary is a text element that aims to present the meaning of unknown terms within the text to the reader. The glossary may also be able to explain specific parts of the text giving additional information, or a historical context that allows the reader to have a greater understanding of the text, especially when reading an archaic text or text from a different culture.
The glossary can be presented at the end of the text or on the side of the page, to make the reading more optimized.