Here is a food chain:
The GRASS is called a PRODUCER because it is a plant and makes the food that feeds the animals.
The RABBIT and the FOX are called CONSUMERS because they eat the food made by the grass:
the rabbit is a FIRST CONSUMER (it eats plants) and is PREY for the fox,
the fox is a SECOND CONSUMER (it eats the rabbit) and so is a PREDATOR.
You can see that the food made by the grass (from air and water) flows along the food chain to the fox.
Nothing feeds on the fox so it is called the TOP PREDATOR.