High Learning increases experience gains. For every 1 xp you gain (remainders are accounted for exactly, there is no rounding loss), you gain Le/1000 bonus xp.
The Good Learner and Great Learner talents increase xp too. Good Learner alone is 150%, Good Learner + Great Learner is 120%. Remainders are accounted for incorrectly and there is rounding loss for many small kills.
These bonuses cumulate additively. Gaining 1000 xp with Good Learner and 99 Le will result in 1599 xp.