He told the members of the Freedom Caucus that he wasn't concerned with the s**t details---or in other words, with the policy of the healthcare bill he tried to inflict on us.
It's worse than that. For all his bluster about it during the campaign, he couldn't be bothered to learn the details. He couldn't discuss them, because he didn't know them. This was going to be Trump Care, just like Trump Steaks and Trump Wine (ew).
Trump is the guy with the big ideas -- it's for his people to work out the details. Interestingly, that's exactly how Obamacare happened, too.
So, when pressed, he did what he always does -- he deflected and attacked. The details were "sh*t details," not important because not in his head.
Note, too, the role of the Freedom Caucus in that story: they were trying to do an end-around on Ryan by trying to make deals with Trump. Think about that for a moment: how is that helpful? How did they expect that to work out? They make demands of Trump, Trump orders Ryan to make changes and....? Were they hoping Trump would get his hands dirty for them? Were they that out of touch with Ryan that they couldn't talk with him directly, and vice versa?