That regex “\s*,\s*” means:
s* any number of whitespace characters
a comma
s* any number of whitespace characters
which will split on commas and consume any spaces either side
s stands for “whitespace character”.
It includes [ tnx0Bfr]. That is: s matches a space( ) or a tab(t) or a line(n)
break or a vertical tab(x0B sometimes referred as v) or a form feed(f) or a carriage return(r) .
\s*,\s*
It says zero or more occurrence of whitespace characters, followed by a comma and then followed by zero or more occurrence of whitespace characters.
These are called short hand expressions.
You can find similar regex in this site: http://www.regular-expressions.info/shorthand.html