See link. Basic facts of the case are the following, think this is a pretty neutral description:

• The Republican majority in Alabama drew new voting districts for Congress, as is happening in all states. Of the seven districts, one is majority Black. Based on the proportion of Black people in the state and its history of racial discrimination towards them, especially in voting rights, many people are arguing there should be two majority Black districts - but the Republicans drew the maps in such a way as to limit it to one, as obviously Democrats would be favoured to win in majority Black districts.

• So they sued. The District Court overturned the new map and ordered the Alabama legislature to redo it. Alabama appealed to the SC, asking also that until the SC can hear the case in full, the District Court's decision be put on hold - in other words, considering the timeline of a full SC case, that the 2022 election would go ahead with the map as it stands, with any potential changes ordered by the courts to apply only for subsequent elections.

• As you see in the opinion, the conservative majority is agreeing to the stay, so to hold the 2022 election based on this map. The liberal three are objecting to the stay and making clear they'd support the District Court's opinion also in the full case. Roberts is withholding judgement on the merits of the full case, but also wants to deny the stay and let the DC's order to redo the maps before the 2022 election stand.