The previous anime premiered last October, and began with the “Porori Arc” story, before it entered the “Silver Soul” arc on January 7. The anime entered into a hiatus after episode 353, which aired on March 25.
Silver Soul is the title of the manga’s final arc that began in July 2016. The anime’s return on July 8 will be for the “climax” of the Silver Soul arc. Rock band SPYAIR will perform the new opening theme song, and music group CHICO with Honeyworks will perform the new ending theme song.
Crunchyroll streamed the previous anime as it aired in Japan.
Source: Gintama volume 73