Learn Dutch: Dat lampje is heel leuk. - That little lamp is very nice.

We use dat for het words (neuter words) and die for de words. Because lampje ends in -je, it is a diminutive (meaning a "little" version of something). In Dutch, all diminutives are automatically het words, so we have to use dat.

But I thought the word for lamp was de lamp. Does the gender actually change?

Exactly! The base word is indeed de lamp, so you would say die lamp for "that lamp". But as soon as you add the -je to make it lampje, the word becomes a het word. This gender change happens to every single word when you turn it into a diminutive!

Does heel mean "very" or "whole"?

It can mean both, depending on how it's used in the sentence! When used with a noun (like een heel brood - a whole loaf of bread), it means "whole". But when you put it directly in front of a describing word like leuk (nice), it acts as an adverb meaning "very".

I learned that leuk means "fun". Why is it translated as "nice" here?

Leuk is a very common and flexible word in Dutch. It can definitely mean "fun" when talking about an activity or an event. However, when you use it to describe a physical object like a lamp, it usually translates better to "nice", "cute", or "pretty".