These are negative energies expressed verbally in a strong way to harm someone. When someone is hurt emotionally by you, that person can send very powerful curses and spells to you
Curses can be found on countries, villages, families and even many generations in a lineage.
Example 1: Some strong guy is bullying/ hurting someone who is weak, this guy who is hurt can send out lots of negative thoughts in the form of curse.
Example 2: Husband / mother-in-law torturing the lady can receive lot of curses from the lady.
Example 3: Sometimes we say this land or county is cursed due to what has been done ages ago. These are places which were long ago conquered, where wars have been fought and where innocent people have been tortured and killed.