What does that mean "Duraion" on the Log Detail?

Hi, 

I'm looking at the "timeout" log, but I don't understand what the value displayed in 'Duration' means, like the attached file.

The attached file shows that duration value is '10s'. That means the action did 'timeout' because there was no response from the destination IP for 10 seconds? (The service port is HTTP)

Is that value not related to the "session-ttl" value?

    config system session-ttl         set default 3600     end

Thanks.