Write text in TikZ Drawing
Use the [label=<position>:<text>]
option format along with your nodes, like this:
\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{arrows.meta}
\begin{document}
\begin{tikzpicture}
\begin{scope}[every node/.style={circle,thick,draw}]
\node[label=below:text] (0) at (0,0) {0};
\node (1) at (1,1) {1};
\node (2) at (1,-1) {2};
\node[label=below:text] (3) at (2,0) {3};
\node[label=below:text] (4) at (-2,0) {4};
\end{scope}
\begin{scope}[>={Stealth[black]},
every node/.style={fill=white,circle},
every edge/.style={draw=red,very thick}]
\path [->] (0) edge (4);
\path [->] (0) edge (1);
\path [->] (1) edge (2);
\path [->] (0) edge (2);
\path [->] (1) edge (3);
\path [->] (2) edge (3);
\end{scope}
\end{tikzpicture}
\end{document}
\documentclass[tikz, margin=3mm]{standalone}
\usetikzlibrary{arrows.meta}
\begin{document}
\begin{tikzpicture}[
C/.style = {circle,thick,draw, inner sep=2pt},
every edge/.style = {draw=red,very thick,-{Stealth[black]}},
]
\node[C,label=below:text] (0) at (0, 0) {0};
\node[C] (1) at (1, 1) {1};
\node[C] (2) at (1,-1) {2};
\node[C,label=below:text] (3) at (2, 0) {3};
\node[C,label=below:text] (4) at (-2,0) {4};
%
\draw[->] (0) edge (4)
(0) edge (1)
(1) edge (2)
(0) edge (2)
(1) edge (3)
(2) edge (3);
\end{tikzpicture}
\end{document}
In using labels you need to consider, that labels are actually nodes, therefore defined style for main nodes with every node/.style
affected labels to. Above code gives: