sentence structure

바른티나 가 studies ㅡㄴ 한국사람ㅔㅛ.
=>바른티나가  한국말을 공부하고 있어요
Valentina is studying Korean.
Note: I'm not 100% sure what you wanted to say here.

저는 바른티나ㅔㅛ.
=> 저는 바른티나이예요.
I'm Valentina

나는 스무세사리ㅔㅛ.
=> 저는 스믈세살이예요.
I'm 23 years old.

1 하나, 2 둘, 3 셋, 4 넷, 5 다섯, 6 여섯, 7 일곱, 8 여덟, 9 아홉, 10 열
10 열, 20 스믈, 30 서른, 40 마흔, 50 쉬은, 60 예순, 70 일흔, 80 여든, 90 아흔

Put ㅇ when you speak only a vowel. e.g. instead of ㅔㅛ,  write 에요.

Nice to meet you (만나서 반가와요) :c)

sentence structure

바른티나 가 studies ㅡㄴ 한국사람ㅔㅛ.
발렌티나가 한국어를 공부해요.
(ok, you're from Ruissian Fed. So I think your name pronounces same as it looks. So it will be 발렌티나. Normally in the states, your name pronounces 밸른티너, and in UK, 발른티나, in Korea we pronounce same as it looks. Anyway, I insist person's name should be pronounced the way his or her country's people pronounce it. So I would stick with 발렌티나 better)

저는 바른티나ㅔㅛ. 나는 스무세사리ㅔㅛ.
저는 발렌티나예요. 저는 스물 세 살이에요.

Very nice to meet you, Valentina. Hope I could help you a little bit. Have a great one.