Several parts combine into one character.

The slug is "lightning" because that is the original meaning. Oracle bone 電 shows a lightning bolt zigzagging out from a rain cloud. For three thousand years the character meant only natural lightning. Then in the 19th century, when CJK languages needed a word for the newly understood phenomenon of electricity, they reached for the closest natural analog: lightning. So today 電 / 電 / 电 covers both senses, with everyday speech leaning heavily on the modern "electricity" reading.

Three forms: 繁體 電 / 新字体 電 / 简体 电. Simplified Chinese drops the rain radical entirely, keeping only the bolt below.

Mandarin: diàn, falling 4th tone. The compounds are everywhere: 电话 (diànhuà, telephone — "electric speech"), 电视 (diànshì, television — "electric vision"), 电脑 (diànnǎo, computer — "electric brain"), 电影 (diànyǐng, movie — "electric shadow"), 电池 (diànchí, battery — "electric pool"), 电梯 (diàntī, elevator — "electric ladder"), 闪电 (shǎndiàn, lightning — "flash electric"). Modern technology vocabulary in Chinese is mostly built by prefixing 电 to native words.

Japanese: on-reading デン (den) for both senses — 電気 (denki, electricity), 電話 (denwa, telephone), 電車 (densha, electric train), 電池 (denchi, battery), 停電 (teiden, blackout). The kun-reading いなずま (inazuma) means lightning specifically — but uses 稲妻 ("rice-stalk wife") for that ancient agricultural metaphor, not 電.

Memory aid: rain on top, lightning bolt below. The character is a thunderstorm.