Bands are groupings of frequencies where stations are located. Examples:

AM Broadcast Band - 535,000 Hz to 1,605,000 Hz which is the same as 535 KHz to 1605 KHz
FM Broadcast Band - 88,000,000 Hz to 108,000,000 Hz which is the same as 88 MHz to 108 MHz

Do the best you can on memorizing these: