This is the 4369th most frequent Polish word.
gęsto
"Densely" or "thickly."
Here, 'gęsto' is used to describe the density of the vegetation in the forest.
Las był tak gęsto porośnięty, że trudno było się przez niego przedrzeć.
The forest was so densely overgrown that it was hard to get through.
In this case, 'gęsto' is employed to characterize the frequency or density of raindrops.
Deszcz padał gęsto, utrudniając widoczność na drodze.
The rain was falling heavily, making visibility difficult on the road.
'Gęsto' is used here to indicate that the placement of items on the table was very close together.