Mary has my full confidence.
我完全信任玛丽。
名词confidence有两个主要的意思:对自己的信心,自信(A feeling of assurance, especially of self-assurance.);对别人的信心,信任(Trust or faith in a person or thing.)。这句中使用的是后一种含义。
再如,I have every confidence in your ability to succeed.
我绝不怀疑你取得成功的能力。