See the perldata manpage for complete documentation.

There are three basic data types in perl:

1. scalars: In perl, a scalar is a variable which holds a single value. That can be a number (int or float) or a string or a reference.
2. arrays: An array is a list of scalars.
3. hashs: A hash is also a list of scalars, but one whose elements are named.

In addition to these three, perl also has: typeglobs, a group of variables which share an identifier; objects, blessed variables that are aware of what they are; and references, scalars which point to other variables, data or subroutines.

Perl 5 Pocket Reference