When copper turnings are added to silver nitrate solution, a blue coloured solution is formed after some time. It is because, copper

Cu is above of Ag in electrochemical series and thus $\mathrm{Cu}+2{\mathrm{Ag}}^{+}\to {\mathrm{Cu}}^{2+}+2\mathrm{Ag}$ reaction occurs and it displaces Ag from its salt solution.

${{\mathrm{AgNO}}_3}_{\left(\mathrm{aq}\right)}+ \mathrm{Cu} \to \mathrm{Ag} +{\mathrm{CuNO}}_{3\left(\mathrm{aq}\right)}$