This is the 465th most frequent Czech word.
květnu
"Květnu" means "May" (the month) in the dative case in Czech.
The word 'květnu' is used in its locative form to denote the time period being referred to.
V květnu obvykle kvetou květiny.
In May, flowers usually bloom.
Here, 'květnu' again appears in the locative case to specify the time the event is planned.
Chystáme zahradní slavnost v květnu.
We are preparing a garden celebration in May.
'Květnu' is used in the locative form as part of a time expression, indicating when the action occurs.