I'd heard it was from Europe, but I didn't know the details, so I looked it up this time.

Then I found that it was thea religious story about St. Valentine infrom the 3rd century AD.

However, now it is thea day for couples, especially in Japan.

It is quite common in Japan thatfor a woman to gives a chocolate to her boyfriend on this day.

So, although it's a very commercial event nowadays in Japan, but it might be good that femaleswomen have thea day to tellexpress their love to their partner.

Here, it would be more appropriate to say women, rather than females. Also, using 'although' here sounds more natural.

If you have time, it'sd be so useful for me that youif you could teach me to teach me the difference between "woman" and " female".)

'Female' is used in more biological/anatomical/medical contexts. In most regular conversations, you'd say woman. Hope that helps!

Then I found out that it was thea religious story about St. Valentine in the 3rd century AD.

ISo that means that Valentine's Day is actually related to Christianity.

However, now it is thea day for couples, especially in Japan.

It is quite common in Japan thatfor a woman to gives chocolate to her boyfriend on this day.

It seems that one think a Japanese food company tried to hold an event that contributed to its profitjust to make money in February.

I'm a bit confused by "contributed to its profit". So, apologies if my correction isn't accurate.

So, it's a very commercial event nowadays in Japan, but it might be good that femalesfor women to have thea day to tellfor showing their love tofor their partner.

"Female" feels weird here, explained below.

If you have time, it's sod be really useful for me that youif you could teach me the difference between "woman" and " female".)

"Female" is exclusively biological. To me, it feels a bit awkward when used to refer to people outside of a medical context. It might even be a little offensive in some regions of the United States. "Woman" (plural: "women") has a less scientific tone, and is far more commonly said in everyday life (as is "man"/"men" instead of "male"/"males").

I could also try to write about "biological sex" and "gender", but that's a long story. If you don't know anything about that and want to know more, Wikipedia explains it pretty well: https://en.wikipedia.org/wiki/Sex%E2%80%93gender_distinction