My fever is rising steadily.
Let's go up to the 3rd floor using the elevator.
Smoke is rising.
This word consists of kanji with hiragana attached. Because the hiragana ends with an う sound, you know this word is a verb.
This is an intransitive verb. That means it does not take a direct object. The kanji means above so this means something rises. For example: A fever rises. The sun rises. See? No direct object here. That's why this verb means to rise or to go up.
Since this word has okurigana (hiragana attached to the kanji) you can guess that it uses the kun'yomi reading, which also happens to be a reading you didn't learn when you learned the kanji. Let's use a mnemonic for the kun'yomi reading now, though. You have to remember at least the あ part to read it.
You know that this word means to rise. Imagine something just rising on its own, like a floating tree or something. What would you say? Probably a "surprised" sound. Maybe you'd scream "あ!" when you saw this floating tree.