The slope at that point in that direction will also be 0, and that is our minimum point.

该点在该方向的斜率也将为 0，这就是我们的最小点。

Because at this minimum point, I guess you could say in three dimensions, this minimum point on the surface is going to occur when the slope with respect to m and the slope with respect to b is 0.

因为在这个最小点， 我想你可以说在三维空间中，当相对于 m 的斜率和相对于 b 的斜率是 0 时， 表面上的这个最小点就会出现。