You want a list of everyone that will retire within a year from any point in time, or within a year from today? Within a year from today then first create a variable OneYearFromNow and set it to addYears(‘[%CurrentDateTime%]’,1) and compare Retired_Date to that one. But I guess you need the other one.
Your problem is the ‘-’ because you can not do calculations with dates in an xpath-restriction. So do get this, which will give you a list of object :
Loop over that list in your microflow and check on the other restriction there.
Mind you, ‘[%YearLength%]‘ is nothing more than the number 365. Putting you off by one day in leapyears. Better is to use year-from-dateTime, add 1 and parseDatetime.
This is bound to take time, so if the entity you are retrieving from has a lot of objects, and you need it fast, use OQL.