им нельзя доверять

you can't trust them

→ он
phrase Rare #52,352
you can't trust them Им means “them” in the dative; нельзя + an infinitive expresses that something must not or cannot be done.
RU: Им нельзя доверять, они часто лгут.
EN: You can't trust them; they often lie.

Мэри, им нельзя доверять.

Mary, they can't be trusted.

— Приключения Паддингтона 2 (2017)

Убивай полицейских им нельзя доверять.

Kill police officers; you can't trust them.

— Гангстер (2007)

Всем им нельзя доверять.

None of them can be trusted.

— Делай как надо (1989)

Им нельзя доверять!

They can't be trusted!

— Семь Самураев (1954)