I am new to excel so let me explain what I am trying to achieve. I have a cell I wish to display "yes" based on if another 3 cells contain "yes". Only if this 3 contain "yes", then the cell will be "yes"
Columns N to Ps should be "yes", the nT would be "yes". See on the image.[1]: 
CodePudding user response：
I'm not sure that the other answer from Jodi would work on all versions of excel (It doesn't on mine).
This should work if you wanted it on each row
=IF(AND(N1="si",O1="si",P1="si"),"Si","Nope!")
If you have excel spill range functionality, you could put this in the first row, and it would spill down to your other cells.
=FILTER(IF(P:P<>"Si","",IF(O:O<>"si","",IF(N:N="Si","Si",""))),N:N<>"")