A menorah refers to a candelabrum, usually one with seven branches. A hanukiyyah is a menorah used specifically on Hanukkah, which includes eight branches, one for each day of the holiday, and one extra branch for the shamash (servant) candle that is used to light the other candles.
Blessings are recited over lighting the candles. One candle is lit for each night. The candle for the first night is put on the right side of hanukiyyah. On each subsequent night, an additional candle is placed to the immediate left of the previous night’s candle, and the candles are lit from left to right, so that the kindling begins with the newest light. Since these lights are holy, it is forbidden to make practical use of them; therefore, a special shamash (servant) candle is used to light the others.