TIMOR DOMINI FONS VITAE

Had a beautiful spring start to the day in Chester, getting there early enough for a stroll & came across this.
Not really sure what it means, all i know is that its ingrained in latin in my mind & its from proverbs.
As with so many of these things it seems moderately threatening & doesnt make a great deal of sense to me.

Explanations welcome please, any blipping theologians out there? ...