Is there a Sunnah prayer for 'Asr, and how many rak'ahs does it have? Is the glorification mentioned in the verse: "And glorify the praises of your Lord before the rising of the sun and before its setting" a verbal glorification or a prayer? And is there a prayer before sunset?

The 'Asr Sunnah prayer is two or four rak'ahs. There are multiple interpretations of the meaning of 'tasbeeh' in His (Allah's) saying, "And glorify the praises of your Lord before the rising of the sun and before its setting." Some say it refers to what was obligated before the five prayers, consisting of two rak'ahs before sunrise and two rak'ahs before sunset, along with the night vigil (qiyam al-layl). Others say it refers to the five obligatory prayers. Still others say it refers to verbally declaring Allah's transcendence. And some say it refers to the two rak'ahs of Fajr and two rak'ahs before Maghrib. As for supererogatory (nafl) prayers before sunset, if they are not making up for a missed regular Sunnah prayer, they are not legislated due to the prohibition against them.