This is the 86th most frequent Slovenian word.
časa
The Slovenian word "časa" means "time" (genitive singular form of "čas").
In this sentence, 'časa' is the genitive singular form of 'čas' (time), used after the phrase 'nimam dovolj' (don't have enough) to indicate a quantity of time.
Nimam dovolj časa za učenje.
I don't have enough time for studying.
Here, 'čas' is in the nominative singular form as the subject of the verb 'mineva' (passes).
Med vožnjo čas hitreje mineva.
During the ride, time passes more quickly.
In this sentence, 'časa' is again the genitive singular form of 'čas,' used with 'nisem imel' (I didn't have) to indicate possession or availability of time.