なら分かるよ

I know that

→ なら
phrase Rare #36,727
I know that Used to say that you know or understand something specific, often in contrast with not knowing or being able to do something else. The sentence-ending よ adds emphasis; this phrase is casual.
JA: 東京のおすすめの店なら分かるよ。
EN: I know some good places in Tokyo.

彼の住所なら分かるよ

I know his address.

フランス語はしゃべれないけどほんの少しなら分かるよ

I can’t speak French, but I understand a little.

修正方法なら分かるよ

I know how to fix it.

フランス語は話せないけど少しなら分かるよ

I can't speak French, but I understand a little.