In Terminal, can I find out the current Finder folder?
The following command will return the path to the frontmost Finder window, if that's what you're looking for:

osascript -e 'tell application "Finder" to get the POSIX path of (target of front window as alias)'


Note that this cannot return a POSIX path if the frontmost window has no POSIX path. So if the frontmost Finder window has an ongoing/finished search, is a smart folder or other magical location (like your Mac under devices, which lists all the mounted volumes and the network).

Search/Smart folder/No Finder window returns:


  execution error: Can’t make «class fvtg» of window 1 of application "Finder" into type alias. (-1700)


And trying to execute the command when viewing your Mac:


  execution error: No result was returned from some part of this expression. (-2763)