This is the 1039th most frequent Swedish word.
hårda
"Hard" or "tough" (plural form).
Hårda is used here to describe the physical hardness of the books' covers.
Böckerna är hårda eftersom deras omslag är gjort av trä.
The books are hard because their covers are made of wood.
Hård is used metaphorically here to describe the difficulty or demanding nature of the work schedule.
Hon har en hård arbetsschema, vilket gör henne trött.
She has a hard work schedule, which makes her tired.
Hårda in this context refers to the toughness or strength of the opponents in a competitive sense.