GMO stands for a genetically modified organism.
This means that scientists genetically engineer an organism, usually to change it or take its best trait from it to create a new organism that is more efficient.
An example is growing crops. Scientists may take two crops, one that is highly nutritious and the other that is drought resistant. Genetically engineering them to form a new plant will create a GMO - that will most likely be highly nutritious and also drought resistant - thus two good qualities from two different plants were taken and modified to be in the one plant.
GMO is a very clever and sufficient way for farming as they can grow stronger and won't as easily die and shrivel away. However, they can also be dangerous to eat since they've undergone genetic modification.
Hope this helps.
