The scene is Banquo and Macbeth meeting the witches. The witches are telling Macbeth about things that are supposed to happen in the future. It is important because Macbeth spends the entire rest of the play trying to make all of the witches predictions come true.
Act : 4 Macduffs family murdered
OH NO! I'm sorry son!
This scene is showing that the king has been murdered by Macbeth. Macbeth is walking away after murdering the king while he was visiting his castle. This is important because Macbeth is supposed to protect his guests and his guest ended up being murdered while staying with him.
Act 5 : Birman wood moving to Dunsinane
Cut down these trees
This scene starts out with Banquo suspecting that Macbeth might have murdered Duncan. Banquo is hoping that his prophecies will come true because his sons will be kings. Macbeth starts to feel threatened by Banquo because he can tell he's onto him. Macbeth sends 3 murderers to kill Banquo and Fleance while they were riding horses. Banquo is killed and Fleance escapes from the murderers.
Macduff has gone to England to talk with Malcolm about taking Macbeth down. He has left his family home alone without him there. Macbeth finds out that Macduff is trying to take him down from the witches and plans to have his wife and children murdered. Macbeth knows how to hurt someone, by killing the ones they love so they can suffer.
Malcolm is ordering his men to cut down tree limbs for cover. Macbeth will not be king anymore if the birnam woods come to his castle doors. The soldiers used the trees as cover to get closer to the castle.