You'll get by fine in English, but here are a few Icelandic words to help.
Icelandic, the official language, is a North Germanic language similar to Old Norse that has changed little since Iceland’s settlement period. For this reason, the words and pronunciation can seem quite challenging for visitors.
Fortunately, most Icelanders know English and some Danish since these languages are mandatory subjects in primary schools. Many Icelanders are also proficient in one of the other Nordic languages or in German, French, Spanish or Italian. You generally don’t need a phrasebook to get around, but it doesn’t hurt to know a few simple Iceland words and phrases:
Já = Yes
Nei = No
Góðan daginn / Góðan dag = good day
Gott kvöld = Good evening
Hæ / Halló = Hi / Hello
Bless = Goodbye
Takk = Thank you