This is the 227th most frequent Czech word.
letošního
"Of this year"
In this sentence, 'letošního' is used as an adjective modifying 'června' (June), specifying that it refers to the June of the current year.
Letní festival se uskuteční na konci letošního června.
The summer festival will take place at the end of this June.
Here, 'letošního' serves as an adjective modifying 'sklizně' (harvest), indicating this harvest pertains to the current year.
Výnosy letošního sklizně byly mnohem vyšší než loni.
The yields of this year's harvest were much higher than last year.
In this example, 'letošního' functions as an adjective qualifying 'festivalu' (festival), denoting association with the current year's festival.