、、。
What truly matters is not wealth, but people.
Literal
Really important [nominalizer-の] [topic-は], wealth not, human [copula-である].
本当に大事なのは…である ('what is truly important is...') uses の to nominalize the adjective clause and は to topicalize it. ではなく ('not X, but') creates the contrast between 財産 ('wealth/property') and 人間 ('people/humanity'). A moral-philosophical statement.