This is the 12352nd most frequent Turkish word.
hayatlarına
"Hayatlarına" means "to their lives" or "into their lives" in English.
In this sentence, 'hayatlarına' is used to indicate the possessive form (their lives) and a direction (into).
İnsanlar mutluluğu hayatlarına davet etmeli.
People should invite happiness into their lives.
Here, 'hayatlarına' refers to individuals' lives as an indirect object that receives something added to it.
Kitaplar insanların hayatlarına farklı bakış açıları katar.
Books add different perspectives to people's lives.
In this usage, 'hayatlarına' specifies the lives of animals as the indirect object affected by the action.