=CHOOSE(1+(B25<0)+(C25<0), "both above", "above and below", "both below")
I used B25and C25because from your comment I saw that you want to reference these cells.
" " " ", :
=IF(AND(B25<0,C25<0),"both below", IF(B25<0,"below and above",
IF(C25<0,"above and below","both above")))
p.s.
( ) , . :
=IF(AND(B25<0,C25<0),"both below",
IF(AND(B25>=0,C25>=0),"both above",
IF(AND(B25<0,C25>=0),"below and above",
IF(AND(B25>=0,C25<0),"above and below"))))