More information on season 3 of Demon Slayer: Kimetsu no Yaiba will come out on December 10, 2022. It will appear after Demon Slayer The Movie: Mugen Train, which will broadcast on Japanese television on that date. The first episode of the anime version of Mugen Train will also air before the movie. [Thanks, Livedoor!]
Back in February 2022, ufotable announced that Demon Slayer season 3 would cover the Swordsmith Village Arc. The promotional art showed Muichiro and Mitsuri, who are both members of the Hashira. Muichiro is the Mist Pillar and Mitsuri is the Love Pillar. It is unknown what information we will see in December, but it may be a new trailer for the upcoming season.
The Mugen Train movie is the highest-grossing movie of all time in Japan, beating out strong contenders such as Spirited Away. When the anime returned after the first season, it had several episodes before the Entertainment District Arc that basically retold the Mugen Train Arc. Though it did re-animate and add some scenes, the movie and anime versions of Mugen Train were virtually the same. However, the first episode of the Mugen Train Arc in the anime featured a prologue of sorts about Rengoku. This was not in the movie version, and showed his activities before he met Tanjiro and the others.
Demon Slayer: Kimetsu no Yaiba is available on streaming services such as Netflix and Crunchyroll.