Normally, when a city of yours is losing Loyalty even with a Governor, there are precious few options you have to save it. One of those ways is to emergency-build an Entertainment Complex in said city and nearby ones, which unlocks the Bread and Circuses project and allows your Citizens to exert more Loyalty pressure.
With Sakdina active, you no longer need to build Entertainment Complexes to implement this strategy. All you need is to have completed a single specialty district in a city, and you will be able to run its corresponding project while enjoying the same Loyalty pressure bonuses as Bread and Circuses. If you have a neighbor with a vulnerable city you wish to try to flip, you can use the exact same strategy, as the Loyalty pressure works on foreign cities as well.
If you have other incentives to run district projects (e.g. are playing as Brazil and can run Carnival), Sakdina allows you to derive a bit more value from them. Its window of availability, however, makes it inaccessible during the early game (when players often run Holy Site Prayers to earn a Great Prophet and found a religion quickly) and the late game (when Science Victory seekers often run Campus Research Grants in their cities repeatedly to wring out as much Science as possible).
Sakdina – the feudal system in Thai medieval life – placed each individual in a hierarchical system of mutual obligation. Those lower down could call upon favors from those higher up, who were obliged to grant them (within reason), meaning that all levels of society were bound and committed to each other.