This is the 353rd most frequent Ukrainian word.
вогню
"Вогню" means "fire" (genitive or dative case) in English.
In this sentence, 'вогню' is the genitive form of 'вогонь' (fire) and is used to indicate the possession or relation to fire.
Вогню потрібно триматися подалі, щоб уникнути опіків.
Fire should be kept away to avoid burns.
Here, 'вогню' is used in the dative case, indicating the indirect object of adding something.
Додайте трохи дров до вогню, щоб він горів яскравіше.
Add some wood to the fire so it burns brighter.
In this example, 'вогню' is again in the genitive case, describing a possessive relationship, specifically the warmth belonging to the fire.