Liangshan is the Yi Autonomous Prefecture located in Sichuan Province.
They are sitting in a train car making announcements. The man is of the Yi Nationality. The insignia on his teacup is the railroad insignia like this pin.
The Yi people are the 6th largest minority of China. Below is music of the Yi minority.
Norman Bethune was a Canadian surgeon who volunteered to help the People’s Liberation Army in the 1930s. Mao held him up as a model for emulation. See an animated storybook of Norman Bethune here and another collection of storybook pages here.
The man on the left crouched down is holding an abacus to add the measurements.
“Red hearts” refer to the hearts of revolutionaries.