Breakdown of Ég er með regnhlífina af því að það rignir.
vera
to be
ég
I
það
it / there (existential) / the one (n)
rigna
to rain
Questions & Answers about Ég er með regnhlífina af því að það rignir.
Why does the sentence use er með instead of the verb að hafa (to have)?
In Icelandic, the phrase vera með (literally "to be with") is used when you are physically carrying something, wearing something, or have it on your person right now. If you used að hafa, it would mean you own an umbrella in general, but not necessarily that you are holding it at this moment.
Why is the word for umbrella regnhlífina and not just regnhlíf?
The -ina at the end is the attached definite article, meaning "the". Also, the phrase vera með forces the noun that follows it into the accusative case. For the feminine noun regnhlíf, adding "the" in the accusative case creates the form regnhlífina.
Is af því að just a long way of saying "because"?
Yes! Word-for-word it translates to "of it that", but in Icelandic, these three little words group together to act as the standard conjunction for "because".
Why does það rignir translate to "it is raining" when there is no word for "is"?
Icelandic does not have a separate "is doing" (continuous) tense like English does. The single verb rignir covers both "it rains" in general and "it is raining" right now.