Reduplication has many different functions in Chinese, depending on what kind of word is reduplicated.
If a volitional verb (a verb denoting an action performed with will, such as to kick or to jump) is reduplicated, then that illustrates the delimitative aspect, which means that the action is performed to a small degree or in a short amount of time:
1) shuō-shuo ‘say-say = say a little’
zǒu-zou ‘walk-walk = walk a little’
On the other hand, the reduplication of adjectives is a vivid description of the adjectival meaning.
2) hóng-de-huā ‘flowers that are red’
hóng-hóng-de-huā ‘flowers that are really red’
The reduplication of measure words denote totality, i. e. ‘every’.
3) gè-ge rén ‘every person (where gè is the classifier for rén ‘person’)
zhāng-zhang zhǐ ‘every sheet of paper’ (where zhāng is the classifier for zhǐ ‘paper’)
(Li & Thompson, 1989, pp. 28-36)
Li, C. N., & Thompson, S. A. (1989). Mandarin Chinese: A functional reference grammar. Univ of California Press.