Multivariable calculus - Partial derivatives of vector fields

Courses on Khan Academy are always 100% free. Start practicing—and saving your progress—now: https://www.khanacademy.org/math/multivariable-calculus/multivariable-derivatives/partial-derivatives-of-vector-valued-functions/v/partial-derivatives-of-vector-fields How do you intepret the partial derivatives of the function which defines a vector field?