"This food is not good."
Translation:यह खाना अच्छा नहीं है।
You can say the same being a native speaker i can say both means the same ...sometimes it connected with emphaisis like where you want to give more emphasis...- Example- Ye kahna acha nahi hai (ये खाना अच्छा नही है) here emphasis on Food (Khana) which is not good but in second Example- ye accha kahna nahi hai - Emphasize more on aacha (Good) ....but dont sacred...you can say both ..whole India accept same almost ...
This is the most confusing thing. Sometimes Nahin goes in front of the verb, sometimes it goes in back of the verb. I get that sometimes there is emphasis on different parts of the sentence, but that is extremely hard to tell on duolingo, and if most native speakers say either one is fine and acceptable, cant we just accept both on here? steps off soap box lol.