As for now, there is no clickable option to activate to view seconds in the date section of the Taskbar, but there is a registry setting to accomplish that.
Save this to something like taskbar-seconds.reg, apply the file and restart explorer or restart or logout/login.
Windows Registry Editor Version 5.00
[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced]
"ShowSecondsInSystemClock"=dword:00000001