Why does ice melts on contacting to hot objects?

 First you need to understand what second law of thermodynamics tells,it tells about direction of heat flow,and says heat will flow from hotter to colder object(Kelvin-Plank statement)

As you can understand it from heat engine.

Now what happens in the case of ice,simply its entropy increases on contacting to hot reservoir (or simply hot object),and change in its can be written as

ΔS=m.c.ln(T2T1)$\Delta S=m.c.ln({\displaystyle \frac{T_2}{T_1}})$

Where c$c$ is specific heat

T2$T_2$ final temperature,T1$T_1$ is initial.

Entropy is measurement of disorderness of the system,

As it attains heat from hot object its molecule's kinetic energy increases and molecules tents to go away from each other,which causes change in state,and entropy