Is 'profit' often used in singular form or plural form
I feel a little confused by the word 'profit', sometimes it is used in singular form, but other times it is used in plural form

Question

Answer

I would say it is used in the singular most often.  In the singular, it refers more to the CONCEPT of profit (revenue - cost).

The company made a profit this year; it did not go deeper in debt.

In the plural, it is referring to many instances of making profit, for example, the profits from all of its 100 stores.

Answer

I agree that the usage here may seem a little irregular.  It may not be possible to give an easy rule but this may help a little:

a) Singular when talking about the overall performance of a business e.g. Last year XYZ Ltd made a (big) profit (rather than a loss).

b) Plural when talking about the profit made on a group of individual transactions e.g. Market traders made profits yesterday of 10% more than the previous Friday.