2 dices are rolled. which outcome has the lowest probability of occurring?

If an "outcome" just means the number of pips showing, then

2 or 12

If an "outcome" means specifying the value of each die when rolled, then all 36 possibilities have the same chance of happening: 1/36

You must be precise when posing a problem. Also, it;s

one die
two dice
no such word as dices (except as a verb)