While it's not clear exactly how the surname came about, it may have referred to someone living near a source of iodine or who worked with it in some way.
It's important to note that "Yoder" can also be used as a given name, though it's much less common.
If you're asking about a specific context where you encountered the word "Yoder," please provide more information, and I'll be happy to help you understand its meaning.