It's one of my favorite South African-isms.
Its an Afrikaans expression used when someone is facing a challenging or difficult situation, or are about to embark on something that makes them nervous or anxious. The closest phrase we have in English would be 'Good luck,' but that comes nowhere close to capturing it. At all.
It literally means, simply, 'Strength'.
It's used to wish someone the strength to persevere whatever hardship they are experiencing or whatever nerve-wracking situation they are facing.
It's used to call out the strength you already see in someone's heart, even when they can't see it or feel it themselves.
It's used to infuse strength by affirming that you believe in them and their ability to keep moving forward, by the grace of God.
That's why 'Good Luck' would never suffice as a substitute.
Sterkte speaks courage.
And today, sweet Gritty family, it is all I have to offer to you.