After a meeting between Trump and German Chancellor Angela Merkel, a senior German official said that Trump had to have basic trade tenets of the EU explained to him 11 times. Trump continued to ask why the US couldn’t have a unilateral trade deal with an EU member. White House officials described the exchange as “humiliating.”

The European Union enters into trade agreements as a single entity. As a result, none of its individual members can enter into unilateral trade agreements.

Business Insider – Angela Merkel reportedly had to explain the ‘fundamentals’ of EU trade to Trump 11 times
Business Insider – White House officials reportedly said that time Angela Merkel had to explain the ‘fundamentals’ of EU trade to Trump 11 times was ‘humiliating’
Newsweek – Trump Exposed Ignorance During Trade Talk With Merkel, Leaving White House Aides Humiliated: Report
Independent – Angela Merkel ‘had to explain fundamentals of EU trade to Donald Trump 11 times’