find out means discover (e.g. We don’t know where he lives. How can we find out?)
find out that/ what/ when etc., find out about something means get information (e.g. The police never found out who committed the murder)
find something out means discover (e.g. We tried to keep the time of the party a secret, but Samantha found it out.)
finish something off means do the last part of something (e.g. Nearly. I’ll finish it off tomorrow)
fix up a meeting etc. means arrange it (e.g. We’ve fixed up a meeting for next Monday)