This is the 44th most frequent Czech word.
dnes
"Today."
Here, 'dnes' is used as a noun to denote 'today'—a specific current day.
Dnes je krásné počasí.
Today the weather is beautiful.
In this sentence, 'dnes' is used as an adverb to mean 'today,' modifying 'večer' to specify 'tonight.'
Přijdu k tobě dnes večer.
I will come to you this evening.
Here, 'dnes' is the adverb referring to actions taking place or completed on the current day.