\documentclass[a4paper]{scrartcl}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{colortbl}
\usepackage{array}
\usepackage{tabularx}

\newenvironment{competences}
	{\small \tabularx{14cm}{|X|*{4}{c|}}
		\hline
		\rowcolor[gray]{.95} \centering\textbf{Compétences} &\textbf{A} & \textbf{B} &\textbf{C} & \textbf{D}\\
		\hline}
	{\endtabularx}

\begin{document}
	
\begin{competences}
	compétences 1 & & & & \\ \hline
\end{competences}

\end{document}