Here's a breakdown:
3-letter words:
* eon
* son
* van
* eon
* ole
* voc
4-letter words:
* cone
* vole
* love
* lace
* loan
* canoe
* clan
5-letter words:
* alone
* vocal
* colon
6-letter words:
* canoes
7-letter words:
* volcano
8-letter words:
* volcanoes
Total: That's 19 words we can make from the letters in "volcanoes".
Let me know if you'd like to try making words from another word!