Hello Emir,
The given code suggests that 'Tpoc(i,j)' is a temperature variable.
Also, 'GUI 2D HEAT TRANSFER' is one of the several submissions in MATLAB File Exchange on MATLAB Central which is a forum for our product users to interact, exchange information and knowledge, without MathWorks' involvement. Feel free to contact the author of this submission directly for specific questions about the implementation
Kind Regards
~Pravin