This is the 36th most frequent Persian word.
ها
The Persian word "ها" is a plural suffix indicating more than one.
In this sentence, 'ها' is a plural suffix attached to the word 'کتاب' (book), changing its meaning to 'کتابها' (books).
کتابها روی میز هستند.
The books are on the table.
Here, 'ها' as part of 'لباسهایت' is used to pluralize 'لباس' (clothing) and the possessive suffix 'ت' is added to indicate 'your clothes'.
لباسهایت را تمیز کن.
Clean your clothes.
'ها' is used in 'خانهها' to denote the plural form of 'خانه' (house).