Breakdown of Það sem er aðkallandi núna er þessi nýja aðgerð.
vera
to be
það
it / there (existential) / the one (n)
nýr
new
núna
now
Questions & Answers about Það sem er aðkallandi núna er þessi nýja aðgerð.
Why do we use Það sem instead of Hvað for "What" at the beginning of this sentence?
In English, we use "what" both for asking questions and for making statements ("What is urgent..."). In Icelandic, hvað is strictly for questions. When you mean "that which" or "the thing that" in a statement, you must use the pseudo-cleft structure það sem.
Is the abstract phrase Það sem treated as singular or plural for verb agreement?
Does the adjective aðkallandi (urgent) change its ending based on gender or number?
No. Words ending in -andi are present participles. The word aðkallandi literally comes from að (to/at) + kalla (call). When used as adjectives, these -andi words are indeclinable, meaning they never change their endings for gender, number, or case.
Why is the adjective nýja (new) in its weak form here, rather than the strong form ný?
Because it follows the demonstrative pronoun þessi (this). In Icelandic, adjectives must take their weak declension (which usually ends in a vowel like -a or -i) when they come directly after a demonstrative pronoun, just as they do when following a definite article.