Is the woman imprisoned in the painting, for all eternity? Why is the guy so nonchalant about it all?
I think the captive is praying for mercy because she can’t escape the sorceress. I think the captive Almirena’s supposed to be one of the good characters and not evil like the sorceress. But the only Italian I know is Bongiorno Prinipesa!
The woman is Almirena, who is a goodie (i.e. a Christian). She is the love interest of Rinaldo, the titular hero. She has been magically imprisoned by Armida, Queen of Damascus, who is a baddie (i.e. a Muslim). The man is Argante, the King of Jerusalem, which the Christians are trying to conquer and so he is another baddie. Argante has the hots for Almirena, who hopes that he will therefore get her released. But the famous aria is just her general expression of her despair. And if you think this is all rather complicated, this is one of the simpler bits of the plot.
Spoiler. Jerusalem is re-taken by the Christians, Rinaldo and Almirena are re-united and Armida and Argante convert. So, a happy ending all round!