What does a Pokemon nature do in white?

Question

I want to know because people say that their Pokemon's nature is Jolly and that was good. Please help me and tell me what does the following Pokemons' nature do for them:

Tepig (male) - Lonely nature - level 62

Herdier (female) - Adamant nature -level 81

Pidove (male) - Adamant nature - level 24

Emolga (male) - Bold nature - level 57

Meloetta (genderless) - Naughty nature - level 65

Petilil (female) - Calm nature - level 47

                                             Thank you! :)

Answer 1

http://pokemondb.net/mechanics/natures

Rather than just being a superficial ‘personality’, Natures actually
affect the growth of a Pokemon. Each nature increases one of its stats
by 10% and decreases one by 10% (by the time it reaches level 100).
Five natures increase and decrease the same stat and therefore have no
effect.

Comments

+ The natures that not is doing anything. Hardy, Doctile, Serious, Bashful, Quirky

Answer 2

Most natures will increase or decrease certain stats, although there are 5 natures that are neutral and will not affect any stat.

Lonely: +Atk, -Defence
Adamant: +Atk, -Sp. Atk
Bold: +Def, -Atk
Naughty: +Atk, -Sp. Def
Calm: + Sp. Def, -Atk

List of Natures