GIVE ANSWERS - Bahasa Indonesia

Hello! There are few ways to say that.
You can say : Aku tidak mengerti. /I do not understand
- Aku kurang mengerti. / I don’t quite understand (This is a very common way express when you don’t understand something).
- Aku nggak paham. /Aku gak ngerti. /Aku kurang paham.
Those are also another way to express it.

vincent I “saya” don’t “tidak” understand “mengerti/paham” , i don’t understand “saya tidak mengerti/paham”