UNC Law Professor Joseph Kennedy translates from the Latin. A snippet:
“Quid pro quo” is Latin for “one thing for another.” Trump has argued that he did nothing wrong during his phone call with the president of Ukraine last summer because there was no quid pro quo, no explicit request of continued aid for Ukraine for an investigation of Joe Biden, his leading opponent in the next election. A quid pro quo is not essential to a crime or abuse of power, but the president is wrong in any event. No “magic words” are required for a quid pro quo to take place.