to explain it to them, to explain it to him/her, to explain it to you (formal)
Sami pudo explicárselo bastante rápido.
Sami was able to explain it to him quite quickly.
Aún cuando Tom trató de explicárselo a Mary, ella aún no lo podía entender.
Even though Tom tried to explain it to Mary, she still couldn't understand it.
A pesar de que Tom trató de explicárselo a Mary, ella todavía no podía entender.
Although Tom tried to explain it to Mary, she still couldn't understand.
Al menos debe explicárselo a ella.
At the very least, he should explain it to her.
— System crasher (2019)
Tom no tuvo tiempo para explicárselo todo a Mary.
Tom didn't have time to explain everything to Mary.