Mylar plants can also refer to any artificial plants. Mylar is a synthetic material often used to create the flowers on plastic/silk plants. If it is a living plant referred to as a Mylar plant, Aicha is correct it is typically in reference to a hyacinth.
Mylar plant is a name that is used to refer to Hyacinth. It is a bulbous herb from the Hyacinthaceae family and is native to the eastern Mediterranean region which includes Iran and Turkmenistan. The commercial hyacinth or Mylar plant has a single dense spike of fragrant flowers which are available in various shades of red, blue, white, orange, pink, violet, or yellow.
There is no such thing as a mylar plant. Aicha, show me where you found that info.