Glossaries are lists of source terms and their preferred translations. To set up a glossary refer to Working With Terminology.
When a segment, under the Terminology tab, is selected all terms within that segment that are in the glossary are highlighted and shown with their translation word in the Terminology pane. Using the Next Term and Previous Term buttons moves the focus through all terms within that segment that are found in the glossary.
Editing the glossary from the Terminology pane:
Add a term to the glossary, refer to Adding Glossary Terms
Edit a term in the glossary, refer to Editing Glossary Terms
Remove a term from the glossary, refer to Removing Glossary Terms
Insert a term into the the target segment, refer to Inserting Glossary Terms