This is for you to shoo the dementors in your life away:
In the other words, it means expecting the guard(ian).
The relieving things about this meaning, for me, is when I realize that I have the same spells, taught by my parents since I was a kid.
أَعُوذُ بِاللَّهِ مِنَ الشَّيْطَانِ الرَّجِيمِ
I seek refuge in Allah from Syaithon, the accursed one.
Then I become peaceful again.
P.S.: find out your patronus in https://www.magiquiz.com/quiz/whats-your-patronus/ and tell me yours!