赤い (akai) means "red." It is an i-adjective used to describe something that has the color red. For example, you can say 「赤いりんご」 (akai ringo) to mean "a red apple." It's a fundamental color word for beginners.

赤い (あかい) は「red」を意味します。色を表すい形容詞です。例：「赤いりんご」は「red apple」です。