This usage of 系
is a recent slang (from about 1980s) initiated by the commedian duo とんねるず, particularly in a TV show called ねるとん紅鯨団. It is one of the various hedge words that young generation prefer. It means 'the ... kind'. The most popular words are 体育会系
'people who joined a club activity at school that belongs to the 体育会 "association of athletic-related clubs" ', [汗]{かん}キツ系
'someone who stings like sweat' (汗きつ 'severe sweat' is a rhyme with [柑]{かん}[橘]{きつ}). It is often used for mentioning an attribute of a person, but it does not necessarily have to be about a person. Unlike what dainichi writes, it was used more often to classify boys/men rather than girls/women.
I don't know why, but young (and not-so-well educated) people use unnecessary hedge words all over the place in Japan as well as in other countries. Other examples are: ...みたいな
, ...的
. Incidentally, many of these words were introduced by とんねるず. In America, these kinds of people insert the word like
all over the place in a sentence, which started in San Fernando Valley, California.