Mínzú 民族主義, the idea of a common national goal, despite China being comprised of over 100 regional identities. It doesn't necessariply mean one nation state but rather an ideal that variations need not lead to diviseness.
Mínquán 民權主義, government by the people, of the people, by the people. Sun Yat Sen devised these ideas when China was ruled by the Manchus, a non-Han people who despised the Han, although they copied them. Furthermore, China was occupied by western colonial powers who seized concessions from China by military force and unequal treaties. Strictly speaking there's no "right wing' in modertn China, even though some sections of the Goumindang were proto fascist. Obviously who decides who the people are is a moot point, but the basic idea is that government should heed the people. It's much more pervasive than the technical size of the electorate and limited franchise. Basically it means that governments have a responsibilty to those who they rule.
Mínshēng 民生主義, government for the welfare of the people.As in all countries, government is effectively for the controlling elites, whatever they might be in each country, but the general principle links to the Confucian ideals of virtue and benevolence.
Sun Yat Sen was a Cantonese, as were many in his circles. Hong Kong protests, as it has been doing regularly year after year since 1997. Before which, such protests didn't happen (1967 was an aberration).
The five yellow umbrellas form the shape of the Bauhinia, symbol of Hong Kong and part of the Hong Kong flag. The five stars refer to the five stars on the national flag of China. Brilliant image, on many levels.