The first meaning of "jelly" is ゼリー, but it can be translated in many different ways depending on how the word is used in what context.

Please give me more context. At least show a sentence in which "jelly" is used, please.

As we see from the asker's name, it SHOULD be ジェル (jeru). It is written in katakana, where the first letter is the dotted シ, and the second letter is written a bit smaller than the other letters.

Also, we normally use ジェル even though it is not the person's name.

If you are asking how your name is writte in Japanese, it would be ジェル pronounced Je-Ru.
You included Jelly and that would be
ジェリー（pronounced Je-Ree) or ゼリー（pronounced Ze-Ree).
Just in case you want to use it as an adjective (jellied ....), it would be
ゼラチン質の（zera-chin shitsu no...)
If you are American, what you call Jelly as in peanut butter and jelly sandwich, would be jam in Japan: ジャムpronounced　Ja-Mu

If it is something to eat, it's ゼリー　and if it is something like a hair gel,
then, it is ヘアーワックス　（even when the substance isn't very wax like, they seem to name products this way)