The English version name Garb is another term for clothing, but can also refer to a specific type of clothing. This is a reference to Kin'emon being able to create any type of clothing through his imagination.
As shown by Kin'emon, the fruit has many useful properties. The apparel generated can be used as disguises, but the effectiveness of the disguise heavily depends on the user's capability of imagining it. Apart from serving as disguises, the clothes created by the fruit's power can also be used for other conveniences, such as keeping wearers warm while in a cold environment. This fruit can also create functioning armors and weapons such as swords.
Kin'emon apparently needs to create clothes from leafs or stones, so if there are none in the immediate vicinity then the fruit may not work. The clothes also do not appear to be permanent, and only last as long as they are worn. The fruit also has no offensive capabilities. Besides that, the user suffers from the standard Devil Fruit weaknesses.
By placing a leaf or stone on someone's head, Kin'emon can convert it by saying "Poof" (ドロン,Doron?) into the necessary garb for as long as he can visualize it. The clothes created remain as long as they are worn, but will disappear if removed.
Nami's second coat created by Kin'emon.
Momonosuke's clothes created by Kin'emon.
The armor Kin'emon made for some of the Straw Hats.
As with the Mato Mato no Mi (which was referred to as the "Mato Mato Curse") and both the Nui Nui no Mi and Toki Toki no Mi (both referred as Nui Nui powers and Toki Toki powers respectively), this fruit was not actually named in the manga. Kinemon referred to his "magic" as the Cloth Cloth Jutsu (フクフクの術,Fuku Fuku no Jutsu?) or Garb Garb Jutsu in the English Version. He did say that his ability comes from an unusual fruit that he ate a long time ago.
This fruit is somewhat similar to the Jake Jake no Mi, as they both relate to items of clothing.