localCalendar.set(12, 1) - What that mean?

Few months ago I lost my app on computer and I somehow managed to get my app back from my phone. But when I open it in Andorid Studio there are some mistakes that I don't know what they mean.

Code:

 Calendar localCalendar = Calendar.getInstance();
            localCalendar.setTimeInMillis(this.savedDate);
            localCalendar.set(12, 1);
            localCalendar.set(10, 1);   
            localCalendar.set(13, 1);
            localCalendar.set(14, 1);

My question is: What mean in localCalendar.set() numbers 12, 10, 13 and 14 because Android Studio reports me an error? I know that commands like Calendar.MONTH, etc., are written in that place but I don't know which is which. Pleas help me. Thank you.