This is the 567th most frequent Czech word.
jaře
The Czech word "jaře" is the locative singular form of "jaro," meaning "spring" (the season).
Here, 'jaře' is the locative case form of 'jaro', which means 'spring'. It is used to specify the time during which the action occurs (in spring).
Na jaře kvete mnoho květin.
In spring, many flowers bloom.
Again, 'jaře' functions as the locative case form indicating the time (in spring) when the planting occurred.
Tuhle rostlinu zasadil na jaře.
This plant was planted in spring.
In this sentence, 'na jaře' is used as an adverbial phrase indicating the time context for enjoying the weather (in spring).