willpower; power of faith; power of prayer
An older or more religious-sounding use referring to the power of concentrated thought, belief, or prayer; in modern everyday Japanese, 精神力 or 信念 is often more ordinary for simple 'willpower'.
She prayed for her father's recovery with all the force of her faith.
The common modern sense: paranormal power used to move or affect things by mental force.
映画では、少女が念力で物を動かす。
In the movie, the girl moves objects with telekinesis.
彼は念力でスプーンを曲げられると言った。
He said he could bend spoons with psychokinesis.
I sent my mental energy to a friend far away.
He showed off bending a spoon with telekinesis.
I put my prayerful energy into the charm before giving it to him.