I have a multi valued managed metadata property in office 365 called products and it only generated 2 crawled properties owstaxidProducts and Products. I tried to associate both to refinablestring01 and see some gibberish(seems like some guid and some value) in the refinement panel. Please help.
In case you'd like to get a proper text displayed as a refinable string, you'd need to map ows_NameofYourColumn to a Refinablestring predefined value.
SharePoint crawl is creating two properties for managed metadata columns: ows_ and ows_taxid. The former is a pure text representation. While the later is a value of the managed metadata field with GUID and type associated.
If you'd have initially picked up the wrong mapping and changed it to the correct one later on, you'd need to wait a bit for Search crawler to pickup the correct mapping.
Here is a nice article covering this scenario. It is valid for SharePoint 2013 and SharePoint Online.
You may get help from this link Search Refiners with Managed Metadata