I want to make a forum is shared hosting good for it ? There is no problem with running a forum in shared server, as long as the forum doesn’t exceed the allowed resources. A forum is a website, and no difference from a blog or any other website platform. When your website gets busy with a lot of visitors, using too much RAM, CPU or disk IO, it is time you may start thinking about moving it to a VPS or a dedicated server.
If it’s a new forum shared hosting is fine. Be ready to upgrade to a VPS if your forum gets popular but however shared hosting could still be fine depending on how resource heavy the forum is and what forum software is powering it.