"Have a good day."
Like "itterasshai" (I'm no expert on romanized Japanese) Notice the small "っ" that occurs twice in this word. These indicate that the next kana has a sort of pause before it, making its sound last twice as long,
Secondly, the small "ゃ" after "し" turns 'shi' into 'sha'. This is a single syllable.
So we get something like "i-<sub>-te-ra-</sub>-sha-i" with 7 syllables.
Google translate does a pretty good job of pronouncing it I think: https://translate.google.com/#ja/en/itterashai