They are part of campaigns against Joe Biden and Petro Poroshenko. In Biden's case, seeking to prevent him from becoming President of the USA - one of the accusations has been recycled from the period of the Trump-Ukraine scandal and impeachment and, if I recall correctly, it was originally a distraction from Paul Manafort's indictments (more below).
Ukrainian MP Andriy Derkach obtained these recordings from, he says, "investigative journalists". It is unknown why they gave the recordings to him instead of enjoying a 'scoop'. They are supposedly recordings of conversations between then-VP Joe Biden and Ukrainian President Poroshenko.
I don't think anyone has disputed that the voices are those of Biden and Poroshenko but some say the recordings are heavily and misleadingly edited. That aside, what are they purported to say?
Derkach says they "testify to the facts of international corruption and state treason at the highest state level".
The first topic being "$1 billion in exchange for maintaining Burisma schemes and international corruption" and the demand for the dismissal of then-Prosecutor General Viktor Shokin, "who was investigating the Burisma case and tapped into Biden at that time."
"Biden leaves for Kyiv to put pressure on Petro Oleksiyovych regarding Shokin. There's a powerful argument ... in Biden's pocket ... a $1 billion loan guarantees ... such was a price to save Biden from prison," Derkach said (I think the latter Biden is in reference to Joe Biden's son Hunter).
Now, it is not new information that Joe Biden wanted Shokin gone and used the loan as leverage - he has said so himself! As Trump supporters proved with a YouTube video of Biden saying so on stage in front of a number of people.
The narrative we are supposed to believe is that Biden did so to rescue his son Hunter Biden from a corruption investigation led by the saintly Shokin. But entities that wanted Shokin dismissed included the US government, the EU, the IMF and Ukrainian Parliamentarians and anti-corruption activists. Indeed it was because Shokin was not investigating corruption - and believed to be corrupt himself - that there was international pressure on Ukraine to have him dismissed. Ukraine's Parliament voted on it and Shokin was dismissed.
A second topic of the recordings is about Ukrainian politics, which I don't know enough to comment on.
It's interesting that Kostiantyn Kulyk was present at Derkach's press conference. He was a former prosecutor - fired for failing to attend an exam that all employees of the General Prosecutor's Office were ordered to pass to keep their jobs during a clean-up of the prosecution service.
Shokin and Kulyk are among several disgraced Ukrainian former officials who have tried and failed to persuade US and Ukrainian authorities to investigate Joe Biden. They have also met with Rudy Guiliani to help his campaign of unsubtantiated allegations against Biden.
Derkach is himself accused of corruption by the anti-corruption campaigners Chesno - allegedly appropriating protected lands valued at millions of dollars and failure to properly declare his family's financial interests to Parliament. Also in 2008 Prime Minister Yulia Tymoshenko accused him of embezzling millions.
Derkach met with Guiliani in late 2019 to attempt to build a case against Joe Biden.
Derkach also has ties to Russia and interestingly was once a member of the party that Paul Manafort worked for. Yes, that Paul Manafort, the chairman of Trump's 2016 campaign and former lobbyist, political consultant, lawyer, with convictions of tax and bank fraud, conspiracy to defraud the United States and witness tampering.