Meinst du, wie man Datumsangaben schreibt? Oder wie man sie spricht?

Für das Deutsche ist das schon mal falsch, man schreibt "der 12.10." (ohne Schrägstrich) und spricht "der zwölfte zehnte".

Wie immer kommt es auf den Kontext an: Der 11. September 2001 wird meist 9/11" (nine eleven) genannt, der US-Nationalfeiertag aber "Fourth of July".

Einen Überblick findest du z.B. hier: https://www.wallstreetenglish.com/blog/how-to... - Auszug:

How to write the date

When we write a date we don’t need to add ‘the’ and ‘of’ as we do when we speak. For example:

It’s the first of January – speaking

It’s 1st January – writing

[...]

American vs British English difference

There is a difference in the order of indicating the date and the month between American and British English. In American English it’s common to put the month first followed by the date. For example,

09.25.2019 – September 25, 2019

While in British English the same date is,

25.09.2019 – 25th September, 2019

So be careful when you write a date as numbers as above. Depending who you’re writing to, you may need to write the month to be clear.

Dann gibt es natürlich noch die internationale Schreibweise yyyy-mm-dd: Heute ist 2023-03-2 (in UK auch oft 2023/03/26).

PS: September 25, 2019 is the written form. When spoken, in AE, we would say "September twenty-fifth, twenty-nineteen (or two thousand nineteen.). We would not say, in general, "nine twenty-five". (9/11 is an exception to this rule.)

Note that in online forms, etc. you write the date 01/12/2022 or 22/08/1974, but in other contexts (e.g. proper sentences) you write 1/12/2022 (1.12.2022) or 22/8/1974 (22.8.1974). Written out, in British English it is 1 December 2022, not 01 December 2022.

If you don't mention the year, it would be (again British English) "Let's meet on 1 December for lunch." "Let's meet on 1st December for lunch." "Let's meet on 1/12 for lunch." "Let's meet on 1.12 for lunch."

Note there are no extra dots after the numbers: never write "Let's meet on 1. December for lunch" or "Let's meet on 1./12. for lunch"

In American English it’s common to put the month first followed by the date. For example,

09.25.2019 – September 25, 2019

While much of that material from Wall Street English (which, because of the name, might lead one to believe that it has some connection to New York City, when actually it appears to be located in Hong Kong) does indeed apply to AE, the above example is misleading.

AE does not typically use periods to separate the elements of an all-numeral date and does not typically include leading zeroes in an all-numeral date in normal text. Instead, it uses slashes. Thus, that date would typically be written "9/25/2019" -- although Chicago Manual of Style suggests that the use of all-numeral dates should be limited to non-formal texts (and even then, unless it is clear from the numbers used, i.e., the second element is greater than 12, the month should be clarified somewhere in the text). In formal texts, the month should spelled out, in full or abbreviated as is appropriate. Or, the ISO date of YYYY-MM-DD should be used.

We use full stops in dates. Forward slashes or dashes are also commonly used:

Date of birth: 1.8.1985 (or 1/8/1985 or 1–8–1985)

https://dictionary.cambridge.org/grammar/brit...

Full stops or slashes are often used in dates. 

12.3.09 - American usage: 3/12/09

2.28.15 [sic]- American usage: 2/28/15 

https://grammar.collinsdictionary.com/easy-le...

#1 While in British English the same date is 25.09.2019 – 25th September, 2019

We wouldn't use a comma here in British English.

Like amw, I'd have guessed slashes were more common than dots in the UK. A quick check through the documents I have to hand:

XX/XX/XX - all my debit and credit cards; my covid vaccination card (two handwritten dates by two different people), the expiry date on a discount card, an invoice

XX.XX.XX - UK driving licence, a council tax bill

To summarise for the UK:

At the top of a letter you'd write 25(th) September 2019

In a form, 25/09/2019

Less 'formally' (!): 25/9/2019 or 25.9.2019

In writing, My sister was born on 25(th) September 2019

In speech, My sister was born on the 25th of September 2019

In speech: 2019 = twenty nineteen or two thousand and nineteen (unlike in AE, see #2)

The only exception to day-month-year in BE is 9/11, said nine-eleven.