Questions & Answers about Subite fulmo ekbrilis super la maro.
Subite means suddenly. It is an adverb, so it describes how the event happened.
Esperanto word order is fairly flexible, and adverbs are often placed early in the sentence for emphasis. Starting with Subite gives the sentence a dramatic feeling:
Subite fulmo ekbrilis super la maro.
= Suddenly, lightning flashed over the sea.
You could also place it elsewhere, but the original order sounds natural.
Fulmo is a noun meaning lightning or a flash of lightning.
The -o ending marks it as a noun. So here, fulmo is the thing doing the action.
- fulmo = lightning
- brilis = shone / flashed
So literally, the sentence is something like:
Suddenly a lightning flash began to shine over the sea.
In natural English, we usually just say lightning flashed.