It is a bowl-shaped mesh strainer with a support handle on one end. The support handle continues across the top of the mesh bowl, through the centre. Through it, is the “food mill” part, a crank handle that you turn.
Below the support handle, rubbing against the mesh, is a presser that gets turned with the crank handle. As you turn it, soft food items get pressed through the mesh.
Passoires are usually made of stainless steel, and most come apart to make clean-up easier.
Passoires are good for straining berries, tomatoes, etc.