She's super irritated that they were meddling in the affairs of Macbeth without consulting her first, as she could've done a better job. Also, she points out, Macbeth isn't devoted to them, but to his own ends.
But, FINE, Hecate will clean up this mess. She tells them to all meet in the morning, when Macbeth will come to know his destiny, whatever that means.
Then there's a catchy witch song and dance, and everyone exits after Hecate.
FYI: Some literary critics believe that these scene is way too hokey to be Shakespeare's work, so it must have been added to the play some time between the time the play was first written (1606) and its publication in the first folio (1623), which was after Shakespeare's death (1616). A fellow playwright, Thomas Middleton, may have written the snazzy songs in this scene.
The other noblemen pray that Malcolm and Macduff might be successful and restore some order to the kingdom, even though news of the planned rebellion has reached Macbeth and he's preparing for war.
Sorry to say, it's not looking too good for Macbeth at this point.
3/6
Scene 3
At a park near the palace, the two murderers are joined by a third. Only a bit of light remains in the sky.
Banquo and Fleance approach on horseback and dismount to walk the mile to the palace, as usual. Conveniently, they have a torch—good for seeing by.
Banquo starts up with a friendly "it looks like rain" conversation and is promptly stabbed.
While being stabbed, he denounces the treachery and encourages Fleance to run away and eventually take revenge.
In the meantime, the torch has gone out, and Fleance takes advantage of the darkness to escape.
With Banquo dead and Fleance on the run, the murderers head off to the dinner party to report the half of the job they've done.