The phase velocity of a wave tells us how fast any given phase of the wave is moving e.g. the crest. If we examine some fixed position, then we can count how frequently a full wavelength passes this position as the wave moves with time. This leads us directly to $v = Î»f$.
Beverly Hills, Michigan, in Oakland county, is 3 miles N of Southfield, Michigan and 16 miles NW of Detroit, Michigan. The people of the town are in the Detroit metropolitan area.
Today, we call that place Hillsdale County, Michigan. Although filled with glacial debris from the last ice age, this south-central Michigan county retained prime soil for growing crops, an all important consideration for early 19th century peoples dependent upon an agriculturally-based society.