Surah Ankabout ayat 3

Assalamualaikum, Can someone please elaborate on Surah Ankabout ayat 3 . >But We have certainly tried those before them, and Allah will surely make evident those who are truthful, and He will surely make evident the liars. I have read multiple tafsirs and I am still confused on the wording. If we look at the word by word translation it seems to say that Allah will test people do that he will know. Of course I do know that Allah is all-knowing and he would of course already know but I am confused by the wording of the ayat. May Allah forgive me if I have said something wrong. Jazakallah Khair