“Deliver us from all harm, for you are the commanders of the powers on high!”

Today is the Feast of St. Michael and the Bodiless Powers (angels).  Here is an indepth article on how the Church understanding angels and their work...
Orthodox Teaching on Angels

And, don't forget to greet and honor your guardian angel as well!

Holy angel of the Lord my guardian, prayer for me.
(Canon to the Guardian Angel)