Question

when could we say two bodies are in thermal equilibrium?

Answer 1

When the two bodies attain an equilibrium temperature and when there is no transfer of heat energy between the two bodies we can say the two bodies are in thermal equilibrium.

Answer 2

Thermal equilibrium means transfer of heat from hotter region to colder region. When two one body is transferring heat to another body and when the temperatures of both bodies is equal then it is said to be in thermal equilibrium