Unlike PHP which conflates arrays and hashes, in Ruby (and practically every other language) they’re a separate thing.
http://ruby-doc.org/core/classes/Hash.html
In your case it’d be:
a = {'Peter' => 32, 'Quagmire' => 'asdas'}
There are several freely available introductory books on ruby and online simulators etc.
http://www.ruby-doc.org/