Label edges in tree node (forest)

Question

I have this tree and would like to label the edges but have not been able to find out how. Could anyone explain me how to do thi, please. Any help is appreciated.

\documentclass[12pt, tikz]{article}
\usepackage{answers}
\usepackage{setspace}
\usepackage{graphicx}
\usepackage{slashbox}
\usepackage{enumitem}
\usepackage[colorlinks]{hyperref}
\usepackage{multicol}
\usepackage{booktabs}
\usepackage{amsmath}
\usepackage{mathrsfs}
\usepackage[table,x11names]{xcolor}
\usepackage[margin=1in]{geometry}
\usepackage{float}
\usepackage{amsmath,amsthm,amssymb}
\usepackage[utf8]{inputenc}
\usepackage {tikz}
\usepackage{multicol}
\usetikzlibrary{trees}
\usepackage{tikz-timing}[2014/10/29]
\usetikztiminglibrary[rising arrows]{clockarrows}
\usetikzlibrary {positioning}
\usepackage{xcolor}
\definecolor {processblue}{cmyk}{0.96,0,0,0}
\usepackage{caption}
\usepackage{array}
\newcolumntype{?}{!{\vrule width 2pt}}
\usepackage[spanish, es-tabla]{babel}
\makeatletter
\renewcommand{\@seccntformat}[1]{}
\makeatother
\setlength\parindent{24pt}
\usepackage{forest}
\usetikzlibrary{arrows.meta}

 
\begin{document}
 
\begin{center}
\begin{forest}
for tree = {
    circle, draw, 
    minimum size=5em,
    inner sep=4pt,
%
    s sep=15mm,
    l sep=20mm,
    edge={-Straight Barb} % arrows head defined in 'arrows.meta'
            }
[ItemA
    [ItemB]
    [ItemC]
]
\end{forest}
\end{center}

Answer 1

Use edge label= and complete with what you need (position, style, content).

\documentclass{article}
\usepackage{forest}
\usetikzlibrary{arrows.meta}
\begin{document}
 
    \begin{center}
        \begin{forest}
            for tree = {
                circle, draw, 
                minimum size=5em,
                inner sep=4pt,
            %
                s sep=15mm,
                l sep=20mm,
                edge={-Straight Barb}, % arrows head defined in 'arrows.meta'
                        }
            [ItemA
                [ItemB,edge label={node[midway,left]{left}}]
                [ItemC,edge label={node[midway,sloped,above]{right}}]
            ]
        \end{forest}
    \end{center}
\end{document}

If you need to label more than a few, you would find useful to define a general style inside your forest declaration, like this:

        \begin{center}
        \begin{forest}
            for tree = {
                circle, draw, 
                minimum size=5em,
                inner sep=4pt,
            %
                s sep=15mm,
                l sep=20mm,
                edge={-Straight Barb}, % arrows head defined in 'arrows.meta'
                EL/.style = {edge label={node[midway, fill=white, inner sep=2pt,
                                        anchor=center]{#1}},},
                        }
            [ItemA
                [ItemB,EL=left]
                [ItemC,EL=right]
            ]
        \end{forest}
    \end{center}