An IV is a random number given to each of a Pokemon's stats upon generation. Having higher IVs will increase the stat. I believe that IVs also affect what type Hidden Power is.
There is no way to find exact IVs but they will have a characteristic based on which Iv is the highest. Here are the characteristsics:
Attack
Proud of its power
Likes to thrash about
A little quick tempered
Likes to fight
Quick tempered
Defense
Sturdy body
Capable of taking hits
Highly persistent
Good endurance
Good perserverance
Special Attack
Highly curious
Mischievous
Thoroughly cunning
Often lost in thought
Very finicky
Special Defense
Strong willed
Somewhat vain
Strongly defiant
Hates to lose
Somewhat stubborn
Speed
Likes to run
Alert to sounds
Impetuous and silly
Somewhat of a clown
Quick to flee
There is a page on IVs on the site if you need more info.
