Hi mitra0911,
The Run modes are as explained in their below 3 types.
The above information gives quite a good amount of explanation about its usage. Also it is further explained in the BP Foundation Training course pdf.
Since I haven't come across a scenario of using multiple processes accessing the same object and at the same time on the same resource I cannot give you any examples. You can try out by changing the Run modes and see what happens.
The Run modes are available in the Object under Initialise tab -> Information stage -> Information tab.