documentclass{article}
usepackage{tikz}
usetikzlibrary{positioning,tikzmark}
% positioning used for above= and below=
% tikzmark used for subnode

begin{document}
begin{tikzpicture}[remember picture]
  node{$
    subnode{sign1}{$color{red}-$}
    3
    mathbin{subnode{minusoperator}{$color{blue}-$}}
    subnode{two}{$2$}
    =
    subnode{sign2}{$color{red}-$}
    5
  $};
  node[above=4mm of two] (minussigntext) {
    color{red}  Minus symbol as sign
  };
  node[below=4mm of two] (minusoperatortext) {
    color{blue} Minus symbol for subtraction
  };
  draw [-] (minussigntext)     to [out=230,in= 90] (sign1);
  draw [-] (minussigntext)     to [out=310,in= 90] (sign2);
  draw [-] (minusoperatortext) to [out=110,in=270] (minusoperator);
end{tikzpicture}
end{document}