I updated Spyder to 4.0.1 which has a new object explorer, allowing to display arbitrary objects in a tree-like view as well as displaying metadata
Previous version
(Spyder maintainer here) You need to have Pandas installed in the same Python installation or environment where Spyder is installed. Else Spyder will use the Object explorer to open Dataframes, just as it does with any other kind of Python object.
As per documentation https://www.spyder-ide.org/blog/spyder-variable-explorer/ you can view the dataframe by right clicking on it and selecting the "View with the Object Explorer" option.
Edit: I don't have Spyder 4.0 installed, you can check if this works for you.
Just open up the terminal >> activate the environment that you're working in >> install pandas again. (If you're using conda, install it using conda)