"Grade 7, Class 3" in Engpsh is usually referred to as "Seventh Grade, Third Class."

The format of naming classes in Engpsh typically follows a "grade, class" structure, where "grade" refers to the level of education (e.g. first grade, second grade, etc.) and "class" refers to the specific group of students within that grade level.

For example:

"I'm in seventh grade, third class."
"I'm in grade 7, class 3."
"I'm in 7th grade, 3rd class."

This structure and format of naming classes is widely used in the United States and other Engpsh-speaking countries.