。
Everything is in our favor.
Literal
All-things [topic-は] us [for-に] advantageous [copula-だ].
有利 ('advantageous') is a na-adjective. The pattern X には Y が有利だ means 'Y is advantageous for X,' but here the construction is flipped: 'all things are advantageous for us' — 我々に有利だ. The に marks the beneficiary of the advantage.