Explanation
Expressing 'that's exactly what A is; in other words, B'.
Formation
A (Statement)。それが B (Restatement or explanation of A)。
Detailed explanation
The grammar point A。それがB。can be used to restate or clarify that B is precisely what A means. It emphasizes the essence or definition of A by stating B. It can be translated as 'that’s what A is,' 'that is precisely A/B,' or 'in other words, B.'
Examples
Kare wa benkyou ga dekiru. Sore ga tensai to iu mono da.
He can study well. That's what you call a genius.
Oishii ryouri wo tsukuru. Sore ga watashi no shumi nan desu.
I make delicious food. That's my hobby.
Kanojo wa watashi wo tasukete kureru. Sore ga tomodachi to iu mono da.
She helps me. That's what a friend is.
Hitori de nagai tabi wo suru. Sore ga jiyuu to iu mono da.
Traveling alone for a long time. That's what freedom is.
Practice
Grammar content sourced from hanabira.org.