That means the force you're applying is cancelled by another force, which has got to be the force of friction.

意味着你施加在物体上的力被另一个力抵消了,这个力就是摩擦力

耶鲁公开课 - 基础物理课程节选

So force of friction is yet another force.

摩擦力就是另外一种力

耶鲁公开课 - 基础物理课程节选