Hi there,
First of all I must point out that I have never gotten deep into Greek. However, as a linguist with broad knowledge on IE languages, I can assess this syntagm as Noun (f sg N) + Adjective (f sg N), meaning more or less "this generation". The "more-or-less" is there due to lack of context, which is always important, especially when it comes to older texts such as Matthew 24:34, which I believe is the context for your query.
To find out what the original "generation" really meant, I suggest digging and going back as much as practicable before the Greek translation of the Bible. This is because recently we saw that there was a great error in translation, indicating god was the one taking people into temptation, whilst this is semantically contradictory.
I hope that you'll get a better answer soon :)
Regards,
Filip