I don't have any context provided to base an overview on. You've indicated this should be based "ONLY on this context," but no actual context about "Module:Convert/extra" was included in your message. To write an accurate overview, I would need the specific documentation or information about this module.
AI-generated from the Wikipedia summary — may contain errors.
Module documentation
This module can be used to quickly add a new unit for use with {{convert}}. When satisfied that a unit is working correctly, ask at Module talk:Convert for the unit to be moved to the permanent list of units.
Discovered by embedding cosine similarity (sentence-transformers MiniLM, 384-dim).