Both Perl and Python have bundled help system.
In terminal type pydoc pydoc to get started.
Type f to page down, b to page up, q to exit.
From there you can type any keyword or module name to find out the syntax or info.
Or, in terminal, start Python by python, then type help().
In terminal, type perldoc perl to get a list of topics.
use perldoc -f ‹function name› for specific function. Example: perldoc -f printf.
For keywords (⁖ if, while, for …), type perldoc perlop.
For operators (⁖ == + % x ++ =~ m//), type perldoc perlsyn.
For built-in variables (⁖ @INC, %INC, @ARG, …), type perldoc perlvar.
For doc of a particular module, use the module's name. Example: perldoc Data::Dumper.