Please explain this notation... carefully. Easy points.

Let f : ℝ --> ℝ be defined by the formula f(x) = x². What does the arrow indicate, and so on?

"Let f be a function that maps the set of real numbers onto the set of real numbers be defined by the formula f(x) = x^2"

Connection between 2 numbers

Think about converting vidio
U have avi format vidio
Then u convert it
U get mp4 format vidio

Procedure of convertin u can write

Convert : avi ---> mp4