火 indicates that 煌 related to brightness or flames while 皇 is used for pronunciation. One important note is that phonetic part of a Chinese character normally denotes useful meaning as well. Like 皇 of 煌, which not only decides 煌's pronunciation but also contains the meaning of brilliant.
煌 means brightness or brilliant.
There are generally 3 stages of creation of characters in Chinese.
At beginning, Chinese ancestors used drawings to represent different things, which are Pictographs, Ideographs, and Logical aggregates. In this stage, Chinese characters can be used to mean very specific objects and easily understood by looking at them. However it is very hard to extend their meanings.
2nd stage is to solve the shortcomings of drawings which has poor extendibility. Chinese ancestors started to borrow existing characters to mean totally different things just because they have similar pronunciations. Not long Chinese ancestors realized the big shortcoming of this approach - extendibility is good now but expressiveness become much worse. One character could have tens of meanings. Readability reduced dramatically. All other languages on earth thus stopped at this stage and started to use alphabets to express meanings with pure pronunciations.
However in 3rd stage, Chinese ancestors were so stubborn yet so smart that they did solve the issue by inventing Phonetic Complexes to gain both good extendibility and expressiveness in creation of numerous new Chinese characters. Is not it amazing that there is such an old pictograph language, which was created thousands years ago, can evolve, adapt organically and fit well with new technologies and phenomenons which Chinese ancestors could never possible image?
Now it is time to examine 煌's evolution history: (image get from http://www.vividict.com)
|Learn one Chinese Character a day - 煌|
and also enjoy a Chinese calligraphy with 煌 inside: