This is the 624th most frequent Slovenian word.
njihovi
"Their" (possessive pronoun).
The word 'njihovi' acts as a possessive pronoun indicating ownership (their) and agrees in case, gender, and number with the noun 'prijatelji' (friends), which is plural and masculine.
Njihovi prijatelji so vedno prijazni.
Their friends are always kind.
'Njihove' is the feminine plural form of the possessive pronoun 'njihov', modifying 'rože' (flowers), which is plural and feminine.
Videli smo njihove lepe rože v vrtu.
We saw their beautiful flowers in the garden.
Here, 'njihovo' agrees with 'dejanje' (action), which is neuter singular, showing possession in accordance with the subject.