This is the 170th most frequent Slovenian word.
življenja
"Življenja" in English means "lives" (plural form of "life").
Here, 'življenja' is used in its plural form to refer to 'lives' as a concept or existence.
Včasih življenja niso preprosta.
Sometimes lives are not simple.
In this sentence, 'življenja' is in the genitive case, suggesting it belongs to or defines 'quality' (kakovosti).
Za izboljšanje kakovosti življenja je pomembno skrbeti za zdravje.
Improving the quality of life is important for maintaining health.
Here, 'življenje' (singular) is in its accusative form, used to describe the extent or duration.