Here is a terrific video from YouTuber infamy 23 on executing combos in Mortal Kombat X.
Per infamy 23:
For those who don’t know, it is common to refer to moves in Mortal Kombat games by saying 1, 2, 3, 4.
1 = Front Punch, Square, X
2 = Back Punch, Triangle, Y
3 = Front Kick, X, A
4 = Back Kick, Circle, B
x = Cancel into a special (This is not a button, it is just a notation that we use to indicate when a normal move is being cancelled into a special move. In this video, 114 is being cancelled into DB1, so we say 114xDB1)
So the combo in this video is written: 114xDB1, step forward, F32xBF3