Bologna sausage is a type of meat that people like to eat. It's made by taking different parts of a pig (like the ham, shoulder, and other parts), and blending them all together with spices and salt.
Once everything is mixed up really well, they put it into a machine that makes it into a long tube (kind of like a really fat hot dog). Then they cook it and let it cool down before slicing it up into little circles that you can eat on sandwiches or by themselves.
It's called bologna because it was originally made in a city called Bologna in Italy, but now people all over the world eat it!