Hiragana are basic characters for reading and writing Japanese. Since they're phonetic, they're easier to read than kanji, which are symbolic.
Here's "black magic" in hiragana: くろまほう
Ku-ro-ma-ho-u. Kuro meaning "black," mahou meaning "magic." All phonetic, all very intuitive.
Now here's the same phrase in kanji: 黒魔法
Not phonetic at all! If you hadn't learned which words these symbols represent, you'd have to consult a dictionary. And considering there are thousands of different kanji, most of which have multiple meanings and pronounciations, it can be hard to keep them all straight.