Figurative language is language that is not meant to be taken literally.  It can be a metaphor, which is an indirect comparison where you say something is something, rather than like something.

Since there are some versions of this play where scene 9 is part of scene 8, I have included a link to it to avoid confusion.

Malcolm begins this scene with a euphemism.

I would the friends we miss were safe arriv’d.

They miss their friends because they are dead.  A euphemism is a kind of metaphor used to avoid saying the reality you’d rather avoid talking about.  It is a battle, and soldiers will die.

An example of figurative language from Act 5, Scene 9, is this line from Siward.

Some must go off; and yet, by these I see,

So great a day as this is cheaply bought.

This is a metaphor, because of course you cannot buy a day.  The soldiers are talking about how they wish some of their friends had not been killed in battle.  They bought time with lives.  It is a sad reality.

Malcolm, Siward, and Macduff have a noble cause—to kill Macbeth and take back their beloved kingdom.  However, there is an actual battle going on, and some people will unfortunately die in it.

When Ross tells Siward that his son is dead, he says this:

Your cause of sorrow

Must not be measur’d by his worth, for then

It hath no end.

This too is a metaphor.  Of course young Siward is worth more than his father can mourn.  When Ross says his worth has no end, he does not want Siward to be sad as much as his son was worth, because then he would be sad forever.