Perhaps "I didn't appreciate the significance of the moment" ?

In that moment, I didn't understand the meaning. OR At that time, I didn't understand the meaning.

The first version is better "I didn't understand the meaning" but it would be better to say "at that moment" not "in that moment". Also the word "represent" is incorrect, as you have used it.

I wouldn't say " I like to represent" . I would say the question is.... what does this mean? The meaning of the molment. = what was taken from the event/episode/molment. What did you feel like inside? Did you feel that that time was happy, sad, axnioux, angry, nervous, nauseating, love? christina Reynosa in the comments put the sentence in a good structure for future use.