Again
And Also, Or
adverb, prefix
The meaning of this word and the meaning of the kanji are the same: Again!
This is a very common word, but it's almost always written in kana in casual situations. However, it's often written in kanji in formal contexts, such as official paperwork and legal documents. You'll also see it in some literature, particularly stuff that was written around the time of Miyazawa Kenji and Natsume Soseki.
The reading you learned for the kanji is the same as the reading for this word. You hopefully won't have to learn it... again.
別れを告げ、それから又数年が過ぎた。
They said their goodbyes, and another few years passed.
この書類は、必ず黒のペン又はボールペンで記入してください。
This form must be filled out with a black pen or ballpoint pen.
「僕又来ますね 」と言って、猫はそそくさと帰って行った。
"I'll be back," he said, and the cat hurried off.