Short answers, pulled from the story.
Satya is a Sanskrit word most often translated as "truth" or "essence." It signifies the alignment of one's thoughts, speech, and actions with reality, and derives from the root sat, which carries meanings including "absolute reality," "that which is unchangeable," and "that which pervades the universe in all its constancy."
In the Yoga Sutras of Patanjali, satya is one of the five yamas, or moral restraints. Patanjali defines it as the virtue of restraining oneself from falsehood, exaggeration, distortion, fabrication, or deception, whether through silence or through stating truth without distortion.
The motto of the Republic of India's national emblem is Satyameva Jayate, which translates as "Truth alone triumphs." The phrase originates in the Mundaka Upanishad, which states that truth ultimately prevails and falsehood does not.
In Jainism, satya is one of the five vows prescribed in the Jain Agamas and was preached by Mahavira. Jain teaching holds that the underlying cause of falsehood is passion, and therefore untruth is considered a form of hiṃsā, or injury to living beings.
In Buddhism, satya (Pali: sacca) translates as "reality" or "truth" and forms the basis of the Four Noble Truths, known in Pali as ariya-sacca. These four truths are described in Buddhist tradition as the briefest synthesis of the entire teaching, covering suffering, its origin, its extinction, and the path to that extinction.
In the Rigveda, Ṛta is the principle of cosmic order, balance, and harmony, and it is held to result from satya. Satya is considered essential to the functioning of the universe; without it, Vedic texts hold, reality itself falls apart.