Angels are real!
The concept of their existence, in itself an abstract reality, is not easy for children to grasp. When passing on this reality to them, we need to be careful to steer clear of verging in depicting them in such a way that children connect them to childhood imaginary friends or to some kind of fairy godmother or a tooth fairy!
God sends a Guardian Angel to each person to guide us, to keep us close to Him, to keep us on the right path moving in the right direction towards Him, while protecting us from harm and evil.