Translation:Cái ca này
I'm a beginner but I think this is what's going on.
Đây and Này both translate to "This" in English. However, Đây is a demonstrative pronoun, while Này is a demonstrative adjective.
As a pronoun, Đây can function as the subject of the sentence. Therefore it can be the first word in a sentence. "Đây là cái ca của tôi" means "This is my mug." Đây is the subject of the sentence.
Này on the other hand is an adjective, used to modify the subject of the verb. So "Cái ca này là của tôi" means "This mug is mine." Cái ca is the subject of the sentence, and này is the demonstrative adjective that modifies the subject.
The reason why này goes after cái ca is because in Vietnamese word order the adjective goes after the noun it modifies.
Yes, "Đây" is translated to English as "this", BUT in THIS situation "Này" is the better accepted "this". It may be that "Này" is the only correct "this" in THIS situation.
Why? Because I suppose Này needs to come after the noun. And Đây can be by itself or next to a noun. I usually hear Đây in phrases such as, "Here is ... (some noun)" or "I am over here".
Đây là một bình qua- if i typed it correctly, it should translate to >>>
Here is one flower vase- and no, qua does not mean flower, bình qua means flower vase
Tôi ở bên đây, <<< này can be substituted for đây- not vice versa
Just know that in Việt, you usually need supporting words
Tôi >>> I (the speaker) Ở >>> (signifies location) Bên >>> means nothing by itself Đây >>> this
Bên đây >>> over here