Double click on the word and a popup with the meaning (only English) will be displayed. It shows the various parts of speech and various meanings for the word selected. 

IMPORTANT:
 - According to default behavior of the web page, you will need to reload the page/tab after installing the extension to enable it.
 - By default, all extensions are disabled on Microsoft Add-on pages (including this one). Do not test the extension on this page; it will not work!

You can select the word/phrase by dragging the mouse as well if such words are not double-clickable, for ex. URL links. This mouse selection feature is disabled by default. You can enable it through Dictionary extension icon. 

Attributions:
1) Dictionary API used - https://dictionaryapi.dev/
2) Dictionary Extension icon created by Freepik - Flaticon (https://www.flaticon.com/free-icons/dictionary)