What is an excel formula?

Question

excel

Good day. Can anyone tell me what this formula is, and where you can get acquainted with it in more detail?
Here is the formula itself:

=IF(AND(N15<=2,N15>1.9),1,IF(AND(N15<=1.9,N15>1.3),0.95,IF(AND(N15<=1, 3;N15>0.9);0.9;IF(AND(N15<=0.9;N15>0.6);0.8;IF(AND(N15<=0.6;N15>0, 1);0.5;0)))))

Answer 1

all links lead to N15 - no context what is in this data - some kind of ranking according to the number in this cell

Answer 2

Gives steps like this

Answer 3

Sarcasm counted) Well, if you're being serious?