Short answers, pulled from the story.
Quietist philosophers believe that philosophy has no positive thesis to contribute and instead defuses confusions in linguistic and conceptual frameworks. The role of philosophy is broadly therapeutic or remedial, aiming to liberate the mind by diagnosing confusing concepts rather than advancing knowledge.
Pyrrhonism represents perhaps the earliest example of an identifiably quietist position with Sextus Empiricus describing it as a form of philosophical therapy. Some have identified Epicureans as another early proponent while the neo-Confucian philosopher Cheng Hao is also associated with advocating quietism.
Contemporary discussion of quietism can be traced back to Ludwig Wittgenstein whose work greatly influenced ordinary language philosophers. While Wittgenstein himself did not advocate quietism he expressed sympathy with the viewpoint and his followers shifted focus away from building grand theories toward examining how words are used in daily life.
Quietists take a third position claiming that there is no real debate between realists and non-realists on a given subject. They deny that there is any substantial debate between these positions because the conflict rests on false premises regarding existence and independence.
John McDowell and Jennifer Hornsby argue that when we think truly there is no ontological gap between what we think and what is actually true. Quietists resist the distinction between truth bearers and truthmakers and claim that such a distinction should be eliminated so true statements simply engage directly with reality.