The dimension "Previous page path" is part of Funnel's Google Analytics connector (Universal Analytics).
"Previous page path" is a page visited before another page on the same property. It is typically used in combination with the "Page" dimension.
To get hold of this dimension in Funnel, connect any one of our Google Analytics reports (except Multi-Channel Funnel).
Under the report picker, make sure to select "Page tracking" > "Previous page path"
Working with GA4 Page exploration is not yet supported in Funnel.