赤い (akai) means "red." It's an い-adjective describing the color red. This is a primary color, often seen in things like apples, roses, or stop signs. For example, "赤いりんごを食べました。" (Akai ringo o tabemashita.) means "I ate a red apple."

「赤(あか)い」はリンゴのような色(いろ)。例(れい)：赤(あか)い車(くるま)。