Updates is a tool for installing bundles from the ChimeraX Toolshed. The tool can show all available bundles and their versions in the toolshed, just versions of bundles that are installed, or just updates for installed bundles. Each of the columns can be sorted alphabetically by clicking on the column title.
The Updates tool will pop up automatically when updates to installed bundles are detected. You can control how frequently updates are checked for by changing the Toolshed update interval in the Toolshed settings.
If you choose the Updates tool via the Tools menu, then it defauls to showing all bundles available from the toolshed for the current version of ChimeraX.