please explain...

If you mean the post-credit scene, I have no idea what it means that Toomes shows up in that prison cell. If you're talking about the 2nd post-credit scene, where The Vulture, (who is Arian Toomes/Michael Keaton), is asking Morbius about joining up to make a team, that's in reference to The Sinister Six. A team they were both members of in comics.

I don't think this character is strong enough to have a sequel, or interesting enough to make some team with The Vulture and others to make a movie. But we'll see.......

Toomes from Earth 616 (MCU) was transported during the events of "Spider-Man No way home" into Morbius Earth. As that world Toomes didn't do anything wrong, he was released from prison and directly rebuilded his Vulture suit and try to team up with Morbius.