How many values does the text shadow property takes?

Answer 1

2, 3, or 4...

meaning is implicit:

/* offset-x | offset-y | blur-radius | color */
text-shadow: 1px 1px 2px black;

/* color | offset-x | offset-y | blur-radius */
text-shadow: #CCC 1px 0 10px;

/* offset-x | offset-y | color */
text-shadow: 5px 5px #558ABB;

/* color | offset-x | offset-y */
text-shadow: white 2px 5px;

/* offset-x | offset-y
/* Use defaults for color and blur-radius */
text-shadow: 5px 10px;

/* Global values */
text-shadow: inherit;
text-shadow: initial;
text-shadow: unset;

( https://developer.mozilla.org/en-US/docs/Web/CSS/text-shadow )

Answer 2

Basic text-shadow:
text-shadow: top-offset right-offset color;

Shadow with blur:
text-shadow: top-offset right-offset blur color;

read more at:
http://www.w3schools.com/cssref/css3_pr_text-shadow.asp