一 + 点 + 点 + 地 + Verb
点 (diǎn) is a highly versatile word meaning "point," "dot," or "a little bit." When reduplicated as 一点点, it emphasizes a very small amount, and in the pattern 一点点地, it means "little by little" or "bit by bit."
你能不能说慢一点?我没听清楚。
nǐ néng bù néng shuō màn yīdiǎn? wǒ méi tīng qīngchǔ.
Can you speak a little slower? I didn't hear clearly.
加一点点盐,味道就完全不一样了。
jiā yī diǎndiǎn yán, wèidào jiù wánquán bù yīyàng le.
Just add a tiny bit of salt, and the flavor is completely different.
他的中文一点点地在进步。
tā de zhōngwén yīdiǎndiǎn de zài jìnbù.
His Chinese is improving little by little.