Translation:Actually, it is not my cup of tea.
It is, as in English, a figurative sense meaning: "it is not what I like best" (ce n'est pas ce que je préfère) - and it is an understatement to more or less mean that it is something you really dislike...
And of course, it can also literally be that the cup of tea is not yours.
Google reported that tea did not reach Europe until 1610 (not quite a rebus of 1066) and that the English idiomatic use of 'not my cup of tea' came into use in England in the late 1800s. And because of the reference to tea, I presume that the expression spread from England to France, but when or how, WW I or advertising for some product???
Although linguistic commonalities (cognates, borrowings, etc.) sometimes go back to common linguistic or cultural roots or historic periods of important cultural or trade contact, the much greater scale of such contacts and communication in recent and modern times has led to wholesale international sharing of not only technical and academic concepts and vocabulary, but also those of politics and pop culture. Sometimes, such loan words, are imported in more or less the original form or spelling, or sometimes translated, such as gratte-ciel from skyscraper (such translation loans are called calques).
Idioms and sayings are, of course, trickier, because even if similar ideas are expressed quite possibly because they too have often been passed along, they may be expressed in more local terms or imagery
The English phrase it is not my cup of tea is idiomatic.
Such an idiomatic phrase does not refer to a cup which happens to contain tea. It refers to a completely different subject known to both the speaker and the listener. It is usually offered as an understatement which is to say it is a polite way to express extreme distaste or negative moral judgement about the subject of discussion. It suggests the subject is unworthy of even being discussed unless both parties are in agreement.
The construction Actually, this is not my cup of tea is meant to make it clear that the subject really is about who owns the cup and its contents.
As Sitesurf points out the French phase is about a particular type of container or its contents. The focus is drawn to one or the other by simply changing the preposition.
à = purpose = teacup
de = contents = cup of tea
I understand both the figurative and the literal meaning of "cup of tea" as in "my thing" vs "a cup of tea" as in a drink.
However, duolingo said "This is really not my cup of tea" is an acceptable translation, and my translation was "This is not really my cup of tea", which are both acceptable and identical in the English language.
They can be interchangeable, in English, if you don't care about the difference in meaning. A lot of the time the difference is irrelevant. That doesn't mean there is no difference.
Actually, it is means that it really is ....whatever.
Effectively, it is means that while it isn't really whatever, it might as well be.
"Une tasse de thé" is a noun of noun, where the second noun does not have an article and gives further information on the first noun, in terms of quality, content, material, purpose.
- A cup of tea = une tasse de thé
"Une tasse du (de+le) thé" would be "a cup of the tea" (specific)
A tea cup = une tasse à thé
With "ce n'est pas ma tasse de thé", you cannot distinguish "it" from "this". In theory, "this is not" should be used to translate "ceci n'est pas". In reality, "ceci" is not much used, "cela" a little bit more, but most of the time in the form of "ça", and "ça n'est pas" is interchangeable with "ce n'est pas". The potential "distance" in time or space of "this" vs "that" is usually ignored, so we have to provide translations with "it", "this" and "that" for all occurrences of c'est + a thing.