First values in box-shadow

First values in box-shadow
0.0 0

#1

box-shadow: 0 10px 20px rgba(0,0,0,0.19), 0 6px 6px rgba(0,0,0,0.23);
what are these bold zeros doing in this code. are they ‘offset-x’. then what are 20px and 6px?


#2

y offset and blur radius.