Look up the activity series. This is not a complex concept but you need to be able to think it through. Some hints.
The metals at the top of the list are the most active and will displace any metal ion below it in the series. The metals at the bottom of the list are the least active and will not displace a metal ion above it in the series.
Two definitions will get you through all oxidation/reduction questions. Oxidation is the loss of electrons and reduction is the gain of electrons; LEO the lion goes GER
"Loss electrons oxidation" and "Gain electrons reduction" is a mnenomic that may help you remember. Now you have a try. Post again if you have trouble BUT tell us in detail what you don't understand.