This is the 962nd most frequent Arabic word.
كثير
"كثير" means "many" or "much."
Here, 'كثيرًا' is used as an adverb to indicate the intensity of liking for reading.
أحب القراءة كثيرًا.
I like reading a lot.
In this sentence, 'كثير' is used as an adjective modifying 'الكتب', meaning 'many' in quantity.
لدينا كثير من الكتب في المنزل.
We have many books at home.
Here, 'الكثيرة' serves as an adjective modifying 'المهام', emphasizing their abundance or variety.