A slotted spoon or skimmer is a large spoon, usually with a bowl about 10-12 cm in diameter, made out of stainless steel with - optionally - an insulated (from heat) handle, often plastic. Total length is approximately 35-40 cm. The bowl has circular holes or long slots cut into it, hence its name.
In both cases, the holes or slots enable the liquid (water or oil) to drain away quickly back into the pan, quicker than it would do with a fine-meshed sieve.
In the case of deep fat fryers, these usually have integrated wide-hole wire mesh baskets which perform the same function.