pains
n. uncountablen. great care or effort that you put into doing something correctly. You use this when you want to show that a task was difficult and required a lot of attention.
n. diligent care or significant effort expended to achieve a particular result. Usually plural in form and used in the fixed expression 'to take pains'.
She took great pains to ensure the party was perfect.
The architect took great pains to preserve the original features of the historic building during the renovation.
The historian took considerable pains to verify every primary source, ensuring that the final narrative was as accurate as the surviving records allowed.
Almost always used in the plural form 'pains' with the verb 'take'. Despite the plural form, it functions as an uncountable concept of effort.
he took a pain to helphe took pains to helpIn the sense of making an effort, the word must be plural ('pains') and does not take an indefinite article.