Old SBM and BIN Files Explained
What are .sbm files?
They're an older format for downloaded mods that were copied from Steam's download folder to the local mods folder (%appdata%/SpaceEngineers/Mods/).
They can be opened with any unzipping software because they are a renamed .zip.
The game no longer copies mods like that since 2018 when it switched to Steam UGC API where it uploads loose files and can download updates for specific files instead of redownloading the entire mod.
You can safely delete all the .sbm files from %appdata%/SpaceEngineers/Mods/.
%appdata%/SpaceEngineers/Storage/ also contain .sbm in their name because of old code. E.g. 806331071.sbm_CameraPanning.
These folders are the local storage for mod scripts and should not be deleted unless you know you want to reset their settings.
What is with the .bin file in older mods?
Mods published prior to a 2018 game update would have been compressed and uploaded as this .bin file, which is a renamed .zip format and can be opened with any unzipping software.
You might also find mods that have files+folders and a .bin, in which case it simply means the .bin was not deleted by Steam and can be ignored.
It is not advisable to do changes in downloaded mods folders, including this .bin file, if you wish to clean it up then follow the Fixing download corruption guide to redownload the mod.