Basically he is giving you info on how to interpret the result you got. A t-test (Student's t-test) gives a "p-value" which sometimes comes up in some articles regarding a statistical result. It is a way of assessing whether the result you got is different enough from the expected value (a fair die) taking into account that you can't throw the dice an infinite amount of times. Generally a p-value less than 0.05 is considered statistically significant* and you can trust your result.
You can do the calculation here too if you want to get some values about it and more info.
*) Sort of means that there is only a 5% probability that your result is due to randomness.
Thank fuck.
Though they'll make opt-out soon enough, when the backlash has dwindled down.