Awesome French

Hey there! In one of my texts this sentence - écrire de la main gauche - is said to mean 'to write with one's left hand', however, I'm having difficulty understanding why 'de' was used here. Is there any way you could help clarify? Merci!

Honestly, I can’t explain. I didn’t find ANY clear explanation, and even all the definition I have found always end by “etc” xD “De” is used in so many different ways…