Deepnote provides an easy way to explore the current variables present in a notebook. After executing a cell that defines a variable, the variable will appear in the left sidebar with info about its type and contents.
For some variable types, you can click on the variable to show its rich preview.
This is the variable explorer in action for a pandas dataframe:
Deepnote will also show the rich dataframe preview in the cell output when displaying any pandas dataframe: