"Light" can be countable or uncountable depending on context. Take the sentence "I see the light". If "light" refers to daylight, sunlight or moonlight, it is uncountable. If it refers to a street light, or a stop light, it is countable. I can't think of any example where the plural "lights" would be uncountable.
There's a phrase "het licht zien" which roughly means the same as "to see the light". It can both have the religious meaning (where the phrase originally comes from, I think) and the figurative meaning (to finally understand or believe something one didn't understand/believe before). It has a connotation that the new understanding is the correct one, as opposed to the one held before.