If I may ask about the use of the word 'guarding' used in the English translations of the Quran?

I can understand 'guarding' your private parts from other people, but how can one guard ones private part with 'oneself'? I feel that I'm missing something with the way the word 'guarding' is used. Like the etymology used possibly or the context of the word used in Arabic translated as 'guarding'? Or perhaps the limitations that come with translations that do not give 'justice' to the original Arabic Quran? Inshallah you will help me understand.

I want to make it clear that I do believe masturbation is a sin. I just need help understanding these ayat you've mentioned.

Means guard from haram