Calculation of angles between vectors

Hello everyone
I have a table (Data) that contains a large number of rows in which values of X and Y are found.
What I'm trying to do is get the angles between the vectors that form these points and I do not know if it is possible to do this calculation.
To better understand what I want, I have attached an example of what I want to do automatically, because in order to get what I want first, I must draw these vectors and measure those angles manually and it takes a long time.
In advance thanks for the help