This verse is from the Book of Susanna, which is considered part of the Deuterocanonical/Apocryphal books of the Bible. It recounts the story of Susanna, a beautiful and pious woman falsely accused of adultery.

Here's a breakdown of what the verse means:

"you know that they have borne false witness against me": Susanna is addressing God (or perhaps the elders of the community, appealing to their sense of justice and righteousness). She is stating that the accusations made against her are lies; the men are perjuring themselves. They are bearing false witness (lying under oath) to condemn her.
"and, behold, I must die": This indicates that because of the false accusations and the power held by the accusers, Susanna faces a death sentence. In that time and place, adultery was a crime punishable by death.
"whereas I never did such things as these men have maliciously invented against me": Susanna emphatically declares her innocence. She insists that she never committed the acts (adultery) that the men are maliciously inventing. The word "maliciously" highlights the accusers' evil intent and cruelty in falsely accusing her.

In essence, Susanna is proclaiming her innocence to God (and those who hear her), asserting that she is being unjustly condemned to death based on fabricated lies. She trusts that God knows the truth and appeals for justice.

The verse highlights themes of:

False accusation: The wrongful charge against an innocent person.
Injustice: The unfair application of the law and the abuse of power.
Faith and trust in God: Susanna's reliance on God's knowledge of the truth.
Moral integrity: Susanna's unwavering commitment to righteousness despite the threat of death.