The description of the Gloves of Flame in the Magic Item Compendium 3.5 states:
In addition, five times per day you can utter the word "burn" in lgnnan to generate a flame in the palm of one hand.
Does a character have to be able to speak Ignan in order to activate this effect?
No, the item functions the same as any other command word item.
The character simply needs to know the word used to activate it, whether through being told, a hint on the item, or simple experimentation. Many command words don't even have any particular meaning. This part of the description for the item is simply for flavor.
