A quincunx is when two planets are 150 degrees apart. Alone, a quincunx is a relatively weak aspect, but has difficult tendencies because of the signs they connect.
A Yod occurs when two planets in sextile (60° apart) both form an inconjunct (a 150° angle) with a third planet. The third planet in the inconjunct represents the action point of the Yod; the mid point between the other two planets is the reaction point. The action point of the configuration is sometimes called the "finger of God," and the finger formed by the two inconjuncts points to a place in your chart likely to be very active.
The Yod is believed by many astrologers to be a karmic configuration, and it suggests that there is a compulsive "debt" repayment associated with the area of the chart pointed out.