Japanese translation please?

See : http://haikugirl.me/2014/10/26/word-of-the-week-%E3%82%84%E3%81%A0/

What she's actually saying is いやだ (iyada), which as Alexa said basically just means they don't want to do something. It derives from an alternate reading of the kanji 否, which is normally pronounced "iie", meaning "no". The "da" is simply added as the casual form of the copula "desu". You may on occasion actually hear the expression "iyadesu" from particularly "proper" people, but most would simply just say "iyada".

It's a Japanese slang word, and most Japanese consider it childish (makes sense, since you're talking about a small child) it doesn't have an exact translation, but you say it when you disagree, or when you don't want to do something. The word yada basically means no.