You can read the full memo I've embedded below for yourself, but I'll sum it up for you here.
It doesn't tell us much that we didn't already know, but what it does tell us is not necessarily good news for Trump or those trying to discredit the investigation of Trump.
Republicans have claimed the entire investigation was based on Christopher Steele's "pee tape" dossier, but the Nunes memo makes it clear that the investigation began when the FBI was tipped off by Australian diplomats who spoke to former Trump adviser George Papadopoulos. The memo explicitly states that "the Papadopoulous information triggered the opening on an FBI counterintelligence investigation in late July 2016 by FBI agent Pete Strozk."
The Nunes memo also tells us the FISA warrant on former Trump adviser Carter Page was renewed 3(!) times including 2 times under Trump. We were previously only aware that the warrant was renewed once.
Finally, the memo states that Carter Page was an adviser for the Trump campaign. Trump's people have previously claimed that he wasn't.
Look, I figured Devin Nunes for a fool, but this is one of the biggest self-owns I've ever seen. Nunes released a statement after the memo was released that says he uncovered "serious violations of the public trust" but there is literally nothing in this memo that supports that. That claim is centered around FISA warrants for a bumbling man (Carter Page) who practically screams probable cause every time he opens his mouth.