Expresses obligation or responsibility
Encoding Strategies:
linguistic

debt
something owed
+
-er
verb suffix
Deber means must or should and is related to the English word debt0. Nearly all of its uses connect back to the idea of an obligation that must be fulfilled.0
deber
must, have to, should, ought to (obligation)
If you must or should do something, that's an obligation, like a debt you owe.
Debes llegar a tiempoYou must arrive on time (it's your obligation to arrive on time)
Debemos respetar las reglasWe have to respect the rules (it's your obligation to respect the rules)
must, must be (certainty)
When you say that something 'must' be true, you're expressing your certainty in it.
Debe tener unos treinta añosShe must be around thirty years old
Debe estar en casaHe must be home
to owe
A literal debt you owe to someone, whether it's money or something else.
Te debo veinte eurosI owe you twenty euros (twenty euros is my debt to you)
Le debo un favorI owe him a favor
duty, obligation (noun)
As a noun, a deber is a debt of responsibility, or something you are obligated to do.
Es mi deber proteger a mi familiaIt is my duty to protect my family (it's my obligation)
Cumplir con mis deberes es importanteFulfilling my obligations is important
los deberes
homework, assignment (school)
Your assignments are the tasks you owe your teacher.
No puedo salir hasta que termine los deberesI can't go out until I finish my homework (I owe my teacher this work)
Tengo que entregar este deber mañanaI have to turn in this assignment tomorrow
deberse a [something]
to be due to, to be caused by
When a situation or outcome 'owes itself' to something, that something becomes the reason that it happened.
El retraso se debe a un problema técnicoThe delay is due to a technical problem (the delay owes itself to a technical problem)
Su éxito se debe a años de esfuerzoHer success is due to years of effort (her success owes itself to years of effort)