Breakdown of Það er mikilvægt að þekkja styrkleika hverrar manneskju.
vera
to be
það
it / there (existential) / the one (n)
að
to (infinitive marker)
þekkja
to know
Questions & Answers about Það er mikilvægt að þekkja styrkleika hverrar manneskju.
Why is hverrar used here instead of hver?
It is in the genitive case to show possession, translating to "of each". Because the word it describes, manneskja (person), is a feminine noun, we use the feminine genitive singular form hverrar.
Why does manneskja change to manneskju in this sentence?
It has to match the case of hverrar. Since the phrase means "of each person", manneskja must also be in the genitive case. For weak feminine nouns that end in -a, the genitive singular ending changes to -u.
Is the word styrkleika singular or plural here?
It means the plural "strengths" here. The base word is the weak masculine noun styrkleiki. Because it is the direct object of the verb þekkja (to know), it takes the accusative case. For this type of noun, both the accusative singular and accusative plural are styrkleika, so context tells us it means "strengths".
Why does hverrar manneskju come after styrkleika? In English we say "each person's strengths".
In Icelandic, the genitive phrase (the possessor) almost always comes directly after the thing being possessed. So literally, the sentence is structured as "the strengths of each person". Putting the possessor first would sound very old-fashioned.