How to read PAPI, VASI and OLS lights

PAPI lights (Precision Approach Path Indicators) Are one of the easiest ways to get a perfect landing.
If you are on the correct approach you should see 2 white lights and 2 red lights.
Refer to this image (By Cmglee - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=80089468) for all light configurations.

VASI lights (Visual Approach Slope Indicators) Fulfil the roll of PAPI lights in a more concise form. 3 red on the top row and 3 white row on the bottom means that you are on a good approach.
Refer to this image (By Cmglee - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=80089468) for all light configurations.

OLS Lights (Optical Landing System) are generally used on aircraft carriers due to the fact that they are easy to see when not on a runway. A dot is surrounded by 7 green lights on either side and that dot signifies your approach. A red dot means to low and has it's own colour because if you are to low on an aircraft carrier then you can't go around.
Refer to this image (By Cmglee - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=80089468) for all light configurations.