According to Lennox and the lord to whom he is speaking in Act III, Scene 6, all the problems that Scotland is facing have been caused by the way Macbeth is ruling as king. They hope that he will soon be overthrown so Scotland can be free from tyranny.
The problems that they are complaining about are pretty neatly summed up in the following passage, spoken by "Lord." He says that if Macbeth is overthrown,
we may again
Give to our tables meat, sleep to our nights,Free from our feasts and banquets bloody knives, Do faithful homage and receive free honors.
All which we pine for now
So he is saying that they are going hungry in Scotland. He says that there are murders at feasts and banquets. And he says that people are no longer being honored by the king.
In the play Macbeth by William Shakespeare, the end of the story shows Scotland being plagued by many troubles and the actual play itself shows Macbeth as being responsible for much of the unhappiness.
The numerous references to blood in the play keep these horrible events before our minds and give Macbeth's evil actions a visual illustration. The images also emphasize Scotland's degeneration after Macbeth kills Duncan and steals the throne. Malcolm and Macduff neutralize the damage by restoring good and strengthening the damaged country of Macbeth's destroying. In reality of course, Queen Elizabeth/Mary or King James allegiances and the bloody feuds between protestant and catholic groups were the order of the day
In Shakespeare's Macbeth, Act 3.6, when Lennox talks to another Lord, numerous problems are plaguing Scotland, and Macbeth is the source of those problems.
Macbeth pitied Duncan, and now Duncan is dead. Banquo walked too late, and now Banquo's dead. The two grooms could have served as witnesses, but they are dead. If Malcolm and Donaldbain had not fled, they would be dead. Macbeth is a "tyrant," and Scotland's hope is that England will join with Malcolm and Macduff to dethrone Macbeth and return Scotland to its former state.
I'm paraphrasing, of course, and the literal meaning of what is said in this scene is not exactly as I've stated it. Lennox, in particular, is being sarcastic or ironic, however. I've summed up what the speeches mean, rather than what they literally say.