The top light is apparently to indicate that the salt (!) has run out.
The bottom light is apparently to indicate that rinse aid has run out.
For the record, that seems to be a Zanussi DE-6854 dishwasher, and I found the manual here: (link
"Special salt can be added in one of two ways: 1) If you are using dishwasher detergent that already contains salt, the detergent including the salt is placed in the detergent compartment. - In this case the water softener must manually be set to 1 and electronically to 1 to ensure that the special salt is taken from the detergent container only. 2) If you are using dishwasher detergent and salt separately, the special salt is to be put into the salt container. - In this case the water softener must manually be set to 1 or 2 and electronically between 1 and 5 (depending on the water hardness in your area) to ensure that the special salt is taken from the salt container only. Only use salt specifically designed for use in
dishwashers. All other types of salt not specifically designed for use in a dishwasher, especially table salt, will damage the water
softener. Only fill with salt just before starting one of the washing
programmes. This will prevent any grains of salt or salty water, which
may have been spilt, remaining on the bottom of the machine for any period of time, which may cause corrosion." (Page 6)
"Only use branded rinse aid for dishwashers. Never fill the rinse
aid dispenser with any other substances (e.g. dishwasher
cleaning agent, liquid detergent). This would damage the
appliance." (Page 7)
The manual also explains how to turn the Rinse Aid light off permanently if you do not wish to use rinse aid.