Questions & Answers about Bu, resmî bir yasadır.
Why does yasa have the -dır suffix here?
The -dır suffix is the factual or generalizing copula. While you can often drop the "to be" suffix in everyday spoken Turkish (and just say Bu, resmî bir yasa), adding -dır gives the statement an authoritative, objective, or formal tone. Since the sentence is stating a fact about an "official law," this formal tone fits perfectly.
Why does bir come after resmî instead of before it?
In English we say "an official law", putting "a/an" first. But in Turkish, when an adjective describes a noun that also has the word bir (a/an), the standard word order is Adjective + bir + Noun. So it literally translates as "official a law".
Why is there a comma right after Bu?
The comma is used to show that Bu (This) is the subject of the sentence. Without the comma, Bu could be mistaken for a pointing word attached to the next noun, making it look like "This official...". The comma clearly separates the subject from the rest of the sentence.
What does the little hat on the 'i' in resmî mean?
That mark is called a circumflex. It is used on certain loanwords in Turkish (often from Arabic or Persian) to tell you to pronounce the vowel a bit longer, or to distinguish it from another word that is spelled similarly. For resmî, you just stretch the final "i" sound a little bit, like "res-MEE".