This is the 11221st most frequent Russian word.
густо
"Densely" or "thickly."
Here, 'густо' describes the dense arrangement of trees.
В лесу деревья растут густо.
The trees in the forest grow densely.
In this sentence, 'густо' illustrates the thick atmospheric condition caused by fog.
Повсюду густо висел туман.
Fog hung densely everywhere.
'Густо' here emphasizes the abundant way in which the flowers cover the meadow.