Answer: Filtration technique
Step-by-step explanation:
The technique used here is called filtration.
Filtration,is a physical separation process that separates a mixture of an insoluble solid from a liquid ( acting as the solvent) by the use of a filter barrier that allows only the fluid to pass through.
In the case from the question,
As water is poured over the ground coffee, it forms a mixture of which the insoluble solid is the coffee grounds, the water is the liquid and the filter barrier is the piece of paper which allows only the brown liquid coffee to pass through as the filtrate.