Angels are spirits created by God (Colossians 1:16, Hebrews 1:14).
They are the invisible created things that have a hierarchy - so while we cannot see them we ought to nonetheless be confident of their existence. These invisible created things are spirits meant to serve those who are to inherit salvation - fallen man who now freely chooses Christ. This establishes our relationship with angels in that they are to help us in ways that we may not fully know or understand. However, they aren’t meant to be our servants in an indentured sort of way. We shouldn’t be trying to discover how to boss them around or manipulate them. They are meant to help usher our souls into an eternity with God.