Sh. Mashhūr b. Ḥasan Āl Salmān (حفظه الله) said regarding the purpose of fasting:

“Fasting is obligatory upon us just as it was obligatory upon those before us, as He the Almighty and Majestic stated:

{O you who believe, fasting has been prescribed for you just as it was prescribed for those before you, so that you may attain taqwá}

This fast is a school, and this school, the one who graduates from it must graduate with a certificate, and this certificate is the certificate of taqwá.

But what is taqwá? It is to place a protective barrier between you and what Allāh has forbidden.”

Source: Kayfa Nastaqbilu Shahr Ramaḍān (28m onwards) – YouTube: https://www.youtube.com/clip/Ugkxqzqk8Nu8p9Zb2bXpaaUnmVYUV8EuXIU8