北 Běi is North:
The traditional explanation is that the character is a picture of two people sitting back to back on the North Pole.
Common word: 北京 Běijīng
背 Bèi is 'back'
Common word: 背景 bèijǐng 'background'
南 Nán is 'South':
Note that the element in the enclosure at the bottom is not 羊 yáng 'sheep' as it lacks a horizontal stroke.