Can someone explain what to do on this? I’m really stuck and have to finish this.

you want to write out the beginning of the word in prefix and end of the word in suffix.

Explanation:

A prefix is a group of letters (or an affix) that's added to the beginning of a word, and a suffix is an affix that's added to the end of a word. Prefixes modify the meaning of a word.

the word that best matches the meaning of the expression "went to the big ocean" is died.

the goldfish died, which is why the father looks at the children mournfully. the "big ocean" is the father's way of saying fish heaven. he could have just said that the goldfish died, but this way, the children imagine the fish in a bigger, better place instead of just picturing a dead fish.

explanation: