He will fill, i.e. fully satisfy and supply, our every need--not according to our needs, but according to His riches, which far exceed our needs!
And how does he fill our needs? He fills our needs in Christ Jesus! Christ, the all-inclusive One, is the base, the element, the sphere, and the channel in and by which God cares for His people according to His riches and in glory. What do I really need? How is my need satisfied? Christ is the answer!! All my needs are satisfied in Him because He is what I need.
note 2, 4 & 6 in Philippians 4:19 of the Recovery Version