Colloquial form of 'という' used for quoting, naming, or explaining; very common in spoken Japanese.
彼、昨日来るっていうよ。
They say he's coming tomorrow.
これは『みかん』っていう果物です。
This fruit is called a 'mikan' (mandarin).
要するに、彼は忙しいっていうことだ。
In short, it means he's busy.
その店、安いっていう噂があるけど本当かな？
There's a rumor that the shop is cheap, but is it true?