Can someone explain the speeches of Siward, Malcolm and Macduff to help me?
Act V Scene 4
We learn no other but the confident tyrant
Keeps still in Dunsinane, and will endure
Our setting down before 't.
'Tis his main hope:
For where there is advantage to be given,
Both more and less have given him the revolt,
And none serve with him but constrained things
Whose hearts are absent too.
Let our just censures
Attend the true event, and put we on
The time approaches
That will with due decision make us know
What we shall say we have and what we owe.
Thoughts speculative their unsure hopes relate,
But certain issue strokes must arbitrate:
Towards which advance the war.
Siward is saying Macbeth has enough confidence to stay and face ('endure') a siege ('setting down') of his castle at Dunsinane.
Malcolm is saying a siege is worthwhile because Macbeth's troops are not loyal but forced to serve him (their hearts are not with him, are 'absent'), and both high and low ranks have already deserted him.
Macduff is saying do not concern ourselves now with guilt and excuses, rather get on with the fight. It will be time for judging after the battle is won, when the outcome is known ('true' rather than just hoped for).
Siward agrees with Macduff: do not speculate now, based only on uncertain hopes, about what they should do and who will be on their side if they win. Get on with what will decide ('arbitrate) the matter in their favour, going into battle ('advance the war').