Read Leviticus 16 and you'll learn about the scapegoat, which represented Azazel, part of the sacrificial rituals the Israelites practiced on the Day of Atonement.

https://www.biblegateway.com/passage/?search=Leviticus%2016&version=KJV

Who is Azazel?

Azazel is a fallen angel mentioned by name in the Book of Enoch. The details of why he is represented as a goat are summed up in this article pretty well. Can't vouch for the site otherwise-

https://mythologyexplained.com/azazel-in-the-bible/

Here's the relevant passage from 1 Enoch that shows the similarities between the scapegoat of Levitcus 16 and Azazel.

1 Enoch 10:1-10

1 Then said the Most High, the Set-apart and Great One spake, and sent Uri’el to the son of Lamech,

2 and said to him: 'Go to Noach (Noah) and tell him in my name "Hide yourself!" and reveal to him the end that is approaching: that the whole earth will be destroyed, and a deluge is about to come upon the whole earth, and will destroy all that is on it.

3 And now instruct the righteous man that he may escape, and the son of Lamech to preserve his soul to life, and to escape forever. And from him there will be planted a plant and his seed may be preserved for all the generations of the world.’

4 And again YHWH said to Rafa’el: 'Bind Azaz’el hand and foot, and cast him into the darkness: and make an opening in the desert, which is in Dudael, and cast him therein.

5 And place upon him rough and jagged rocks, and cover him with darkness, and let him abide there for ever, and cover his face that he may not see light.

6 And on the day of the great judgment he shall be cast into the fire.

7 And heal the earth, which the angels have corrupted, and proclaim the healing of the earth, that they may heal the plague, and that all the children of men may not perish through all the secret things that the Watchers have disclosed and have taught their sons.

8 And the whole earth has been corrupted through the works that were taught by Azaz'el: to him ascribe all sins.'

9 And to Gavri’el said YHWH: 'Proceed against the bastards and the reprobates, and against the children of fornication: and destroy [the children of fornication and] the children of the Watchers from among men [and cause them to go forth]: send them one against the other that they may destroy each other in a war of destruction: and length of days shall they not have.

10 And no request that they (i.e. their fathers) make of you shall be granted unto their fathers on their behalf; for they hope to live an eternal life, and that each one of them will live five hundred years.'

To symbolize the duality of the beast and the man. We're all animals, but we're also beings of a higher order than just a beast.