what means impure copper in that link above(like its not only copper,it contains another metal or something)
Impure copper is copper metal that has been produced from its ores but has not yet had its impurities removed. In the web site you gave above the copper that is in the impure block is dissolved in the CuSO4 solution and redeposited on the pure copper cathode. This is the way (at least one of the ways) in which copper is purified. In this process the anode is slowly dissolved and is eventually made very small by the electrolysis process. After the process you will find some of the impurities at the bottom of the container, much pure copper on the cathode, and a greatly reduced impure copper anode. There are a number of impurities in copper produced from its ores that are shown in the link below. In order to have pure copper you must remove those impurities using a suitable method like electrolysis. The impure copper is useful in numerous applications such as copper wire so much of the impure copper is used for house wiring and similar applications.
Robert's answer is correct. This is true of all metals. The highest purity metals humankind knows how to make are about 7 9's (99,99999% pure) based on weight. Electrolysis is only one method of purifying metals, there are many others. hope this helps.
When copper is extracted from its ore, there are other metals and materials that are also present...traces of tin, iron,nickel and traces of sand (silica) ...These will be present in the impure copper. When the copper in purified by electrolysis, the impurities will either stay in solution or drop out as sediment in the bottom of the cell.
