This is the 805th most frequent Czech word.
jaroslav
"Jaroslav" is a Czech male given name, meaning "fierce glory" or "strong glory."
Here, 'Jaroslav' is a proper noun used as the name of the subject in the sentence.
Jaroslav si koupil nový automobil.
Jaroslav bought a new car.
'Jaroslav' is again used as a name, specifying the person who enjoys the activity mentioned.
Můj kamarád Jaroslav rád maluje obrazy.
My friend Jaroslav likes painting pictures.
Here, 'jaro' means 'spring', and 'slaví' means 'celebrates'; together they convey the action of celebrating the spring season. 'Jaro' isn't directly related to the name but could semantically connect by association.