An ore is a rock that contains enough of a metal compound for it to be worth extracting the metal. Most metals are found in ores as compounds, very often metal oxides, such as iron(III) oxide in haematite. To get the metal, the oxygen combined with it must be removed.
Reduction is the loss of oxygen, and oxidation is the gain of oxygen. So extracting a metal from its oxide is reduction: the metal oxide loses oxygen and becomes the metal. Whatever method is used, extracting a metal from its ore always involves reduction.
For example, when black copper oxide is heated with carbon, the carbon takes the oxygen away: 2CuO + C → 2Cu + CO2. The copper oxide is reduced to copper, and the carbon is oxidised to carbon dioxide. Iron is extracted in the same way by heating iron(III) oxide with carbon. The reduction and the oxidation always happen together in the same reaction.