When people talk about "genetically engineered" food, they usually mean a variety of food that was created by changing the DNA of a naturally-occuring plant. For example, a seed company might change the genes of a corn plant to create a new kind of corn that grows more quickly or requires less water.
The technical term for a plant or animal whose DNA has been changed by humans is "Genetically Modified Organism", which is shortened to "GMO". So you may read about "GMO food" or "GMO crops".
Europe has much stricter laws than the U.S. does regarding GMO foods.
But when people are describing the process, they might use the phrase "genetically engineered":
They genetically engineer crops to be resistant to herbicides, so farmers can use the herbicides to kill weeds without killing the crop.