would understand it
Una persona de inteligencia promedio lo entendería.
A person of average intelligence would understand it.
Si papá estuviera aquí, él lo entendería.
If Dad were here, he would understand.
— Jojo Rabbit (2019)
No creo que ella lo entendería.
I don't think she would understand it.
Any child would understand.
— Memories of Murder (Crónica de un asesino en serie) (2003)
Te dije que Tomás no lo entendería.
I told you Tomás wouldn’t understand it.
Se lo habría dicho antes, pero no pesaba que lo entendería.
I would have told him/her earlier, but I didn’t think he/she would understand.