Complex sentence: In verses 15-23 of chapter 2, the Upanishad states that Yoga and Jnana (knowledge) is the way to know the Atman, the Shiva.
Split into simpler sentences: In verses 15-23 of chapter 2, the Upanishad states that practising Yoga leads to "jnana" (knowledge). Together, asserts the text, these lead the yogi to know the Atman, the Shiva.