The containers and tasks themselves do not scale elastically in terms of the resources available, for this reason you have to define the resources that can be used within the task definition.
For each task that is launched in Fargate you must pay for the amount of vCPU and memory that has been allocated. For this reason a single task definition will cost the same amount for each hour that it is running (in fact you pay to the nearest second so you can pay for partial hours).
You will pay for each task for the vCPU and memory that it uses, if you wanted to add more of that task you can increase this capacity in the defined ECS Service so that multiples of the task would be running. If you wanted each task to have more resources you would create a new revision of the task definition and redefine the amount of vCPU or memory that you want to use.
If you scenario you would pay $0.04048
for the first hour, then $0.4048
in the second hour. Although you have not defined the memory you're using so this is not included in the total price.