Guanyin or Guan Yin is an East Asian bodhisattva associated with compassion as venerated by Mahayana Buddhists. She is commonly known as the "Goddess of Mercy" in English and Gayatri in Hindi. The Chinese name Guanyin is short for Guanshiyin, meaning "[The One Who] Perceives the Sounds of the World".
Mahayana Buddhism is just one of many offshoots of Buddhism.
There are many offshoots of Buddhism, that's why there is the Mahayana preface. I suppose this isn't mentioned in the text, but it is common knowledge.
( z1 offshoot :quant ( z2 many ) :mod ( z3 just ) :mod ( z4 religious-group :name ( z5 name :op "Buddhism" ) ) :domain ( z6 religious-group :name ( z7 name :op "Mahayana" :op "Buddhism" ) ) )