Does single-label domain name mean a name like 'OurHouse'. Where as guy.ourhouse.com would not be a single-label domain. If so, would guy-ourhouse.com be a multi-label domain name?
Yes, your assumption is (99%) correct.
What confuses it in a strict technical sense is the implicit '.' on the end of every domain name (at least in the underlying DNS wire protocol) which is a zero length label. However unless you're writing DNS software you don't need to worry about that ;-)
A single-label domain name is where a particular server is just called 'guy' for instance, not 'guy.com' or 'www.guy.com' - just a basic name. Setting up clients to deal with single-label domains is more trouble than it's worth - it's all a bit 'old hat' to be honest, best avoided.