G-d blessed the seventh day and He made it holy: this is speaking about the Shabbat (Shabbos).
What did He bless it with? He blessed it with manna. What is manna? It is an abundance that sustains. It is parnassa. So from keeping Shabbat we are blessed with an abundance of parnassa. Even though we do not work on Shabbat, our parnassa comes from Shabbat. Because we rest on Shabbat and we demonstrate our trust in G-d, He bestows His blessings upon us including the blessing for an abundant livelihood.