Basis period

Having tough time getting this 2nd year rule..i was pretty clear through a flow chart and doing examples as well but right now i am confused when i go through the question “Is there a period of a/c ending in the 2nd year?” and when i go for ‘YES’ it asks, ‘how long is the period of a/c?’ Now this confuses me which ‘period of a/c’ does it mean because normally accounting period tend to be 12 months itself? Is there a better way to get this conceptually??