今日2回目のレッスンです。って英語でなんて言うの？

"This is my second class for the day" This explains to your teacher this is the second class you've had. "I've had one other class today" This tells your teacher that you had a class before this one.

This is my second lesson today. 「This」はこのようの文章のために大切な言葉です。 It's important that you use "This" in order to specify that you're talking about this lesson. You could also let them know that you had another lesson earlier by saying "I've already taken another lesson before this one, so this is my second one for the day" 日本語では「この前に他のレッスンをしたので、これは今日２回目のレッスンです」 "This is my second time taking a lesson today." This sentence uses the word "time" which works the same as the word 回 in Japanese. Also I used the word "taking" to specify the action of doing the lesson. (Taking the lesson)

We use 'only' to stress the fact that this is unusual or new, small or rarely done, or lacking in some way. "I'm only 3 years old." "I'm only a weak woman. I can't lift heavy things "I only spent 2 days in Paris." " That car only has 3 wheels!"

This is my second class today/This is my second lesson today - These are both ways to tell someone you have already had a class or lesson today and that the current one is the second. Class and lesson can be used almost interchangeably in this context. I have already had one lesson today - This is a way to tell your teacher that you have had a lesson that day already and that you're on your second now. So this lesson has already happened.

When you want to tell a teacher that this is the second lesson you've had on the day, you can say: -This is my second lesson today. -I had a lesson earlier. This is my second one. -I had one lesson before this one.