Lionel and Albert are in Westminster Abbey trying to practice for Albert's coronation. Lionel is audacious enough to sit in St. Edward's Chair and Albert is hopelessly trying to get him to move shouting for Lionel to listen to him. Lionel then goes for the "I-don't-care-if-you're-royalty" card and asks why he should waste the time listening to him. Albert then replies, with strong conviction:
Albert: BECAUSE I HAVE A VOICE!
To anyone who's ever had a speech impediment or some other issue that stifles them, this is something powerful.
The King's first wartime speech. Although Albert's speaking has improved immensely thanks to Lionel, he still has tremendous trouble adressing large crowds. In the final speech of the film, not only does he read the entire speech with very little hesitation, he does it over the wireless, broadcasting to every corner of the British Empire. And when he walks out of the broadcast booth, the entire Palace is applauding him. Which doubles as a Heartwarming Moment. Throughout the entirety of speech, with the shots of people all over England listening to what he's saying, and Lionel helping him through the whole time, and to top it all off, Beethoven's Seventh playing in the background.
Winston Churchill praises him. Even if it is fiction, that certainly is an accomplishment in itself.
After being once again berated by the ailing King George V for stuttering, Albert is exhausted and resting at his room. The scene is immensely depressing. And then he takes out the record Lionel recorded of him reading Shakespeare, but with the music played so loud such that he cannot hear himself. His reading is flawless. It's their first realization that Albert can indeed be cured.
Albert and Elizabeth's jaw-dropped expression just adds to it.
What did this troper in, the piece from Shakespeare is the famous "To be or not to be" soliloquy from Hamlet; one of the most famous monologues in literature; literally about whether to accept your fate, "or...by opposing...end them." The most powerful foreshadowing of the movie's theme that nobody is at the mercy of their disabilities.
After the momentary blow-up at Westminster Abbey, the King declares Lionel will sit in his personal boxes. The Archbishop protests as that is only reserved for the King's family and closest friends. The King's reply, "That is why it is suitable," shows that he is becoming more confident in himself, partly due to the fact that Lionel's help made it so that he can express himself.