Short answers, pulled from the story.
The Communal Award was signed by British Prime Minister Ramsay MacDonald on the 16th of August 1932. Also called the MacDonald Award, it followed the failure of the Second Round Table Conference to reach agreement on minority representation in British India.
The Communal Award extended separate electorates to six communities: Muslims, Sikhs, Indian Christians, Anglo-Indians, Europeans, and the Depressed Classes, later known as the Scheduled Castes. It also applied the principle of weightage, which allowed certain communities to claim a seat share larger than their raw population count would have entitled them to.
Gandhi opposed the Communal Award because he feared it would fracture the Indian National Congress and permanently institutionalize caste divisions within Indian democracy. From Yervada Jail in September 1932, he declared an open fast until death and sent his objections directly to the British Cabinet in London.
Ambedkar supported the Communal Award because it guaranteed dedicated electoral representation for the Scheduled Castes, whom he argued could otherwise be permanently outvoted within a general Hindu electorate. He also challenged Gandhi's consistency, noting that Gandhi accepted separate electorates for Muslims and Sikhs but opposed them for the Scheduled Castes.
The Poona Pact was an agreement between Gandhi and Ambedkar that replaced the Communal Award's separate electorate for Scheduled Castes with reserved seats inside a unified Hindu electorate. The separate electorates of Muslims, Sikhs, Indian Christians, Anglo-Indians, and Europeans were left unchanged. The Pact did not extend further political advancement to the Untouchables beyond those reserved seats.
The Akali Dal, the representative body of the Sikhs, strongly opposed the Communal Award. In Punjab, the Award reserved only 19% of seats for the Sikh community, compared to 51% for Muslims and 30% for Hindus, proportions the Akali Dal found deeply unfavorable.