My wife and I watched this at home, streaming. While it is a well-made movie and covers an interesting topic, we didn't find it very enjoyable. It is a movie adaptation of a stage play and it comes across that way, with loud dialog and broad gestures, with limited settings.
It is a Washington family project, Denzel is a producer, one of his sons is the director, another son stars as Boy Willie, and his wife also has a small role.
Samuel L. Jackson is in it but his role as uncle Doaker could have been played by anyone. John David Washington is Boy Willie, he is brash and angry all the way through and after a while I found him hard to watch. Danielle Deadwyler is really good as his sister Berniece. But she is unhappy the whole time because of the bombardment by her brother.
The gist is this, as we see in an opening scene from 1911 in Mississippi when the main characters are children there is a late-night theft of an old upright piano during a celebration event. The piano has sentimental value to the family because of their connection to some wood carvings that adorn the piano. In fact they didn't consider it a theft, they figured they were the rightful owners.
Bernice, now a single mother living in Pittsburgh in 1936, has the piano. However her brother, needing to raise money to try to buy some land back in Mississippi wants to take the piano and sell it. He doesn't make a request, he drives to Pittsburgh with a truckload of watermelons to sell along the way and expects to just take the piano. This creates the discord between the siblings.
The title may lead us to believe it involves piano lessons in the usual way, music instruction, but it isn't. It refers to the lessons a family learns with the piano as a central figure.