Translation:This dictionary app is good.
This modern meaning of 應用 originated from the English word “app (application)”. 应用/應用 orginally means “apply” or “application, appliance”. Combined with 程序/程式 (“program”) or 软件/軟體 (“software”) it becomes another (near-)synonym of “program, software” running on an operating system, especially on a mobile device.
Mainlanders call it 应用程序/应用软件 or 应用 for short. Taiwanese call it 應用程式/應用軟體 or 應用 for short.
I never hear or see mainland Chinese say 应用。It's either 软件 or [the annoying] "A-P-P," which people must have thought stood for three words.
Mandarin speakers can't pronounce hard consonants at the end of syllables. (Though many other Chinese languages/dialects do have final consonants besides n, and ng.) Mandarin also doesn't have the short a sound. Younger Chinese who've studied English don't seem to have this problem but use the same pronunciation as everyone else. All the English abbreviations and acronyms I've noticed in China avoid syllables ending in hard consonants. APP, DIY, KTV, CD, DVD...