Hemp fabric comes from the plant with the same name. It is one of the fastest growing plants and it doesn't need much water, energy, pesticide, or fertilizers. The plant is very good for soil, it can be grown for many years in the same place without exhausting it. This is why hemp is considered to be eco-friendly.
Hemp has very similar properties to linen. They are often difficult to differentiate.
However, as hemp belongs to the same family as cannabis (although it does not have the same psychoactive effects), growing hemp is heavily regulated or prohibited in many countries.