Used to contrast two ideas or add emphasis
Encoding Strategies:
repetition

The most useful translation for pero is but. Nearly every way it's used connects back to a single idea: one thing contrasts with another0.
pero
but
Used to contrast or qualify what was just said.
- Quiero ir a la fiesta, pero estoy muy cansado = I want to go to the party, but I'm very tired
- Estudié mucho, pero no aprobé el examen = I studied a lot, but I didn't pass the exam
but (emphatic)
Used at the start of a sentence to add emphasis or express surprise, without actually contrasting a previous statement.
- ¡Pero qué frío hace hoy! = But wow, it's so cold today!
- Pero ¿adónde crees que vas? = But where do you think you're going?
objection, fault, catch (noun)
As a noun, a 'pero' is literally a "but", as in a fault, objection, or catch. When you raise a 'pero,' you're pushing back with "but..."
- Le propuse el plan y no puso ningún pero = I proposed the plan and he didn't raise a single objection
- Todo tiene un pero con ella — nunca está satisfecha = Everything has a catch with her — she's never satisfied