Things in () separated by commas are called a list of things.
A list is an ordered set of scalar values and variables.
Examples of lists:
(1, 5.2, "apple pie")      # 3 values

(1,2,3,4,5,6,7,8,9,10)     # nice but we are too lazy, so we write this:
(1..10)                    # same as (1,2,3,4,5,6,7,8,9,10)

("apple", "banana", "peach", "blueberry")   # is the same as
qw(apple banana peach blueberry)            # quote word

($x, $y, $z)          # We can also use scalar variables as elements of a list
($x, 3, "foobar")     # or we can mix them