Scatter Plot

\usepackage{pgfplots}
\pgfplotsset{compat=1.17}

\begin{tikzpicture}
  \begin{axis}[
    xlabel=$x$, ylabel=$y$,
    grid=major,
    legend pos=north west
  ]
    \addplot[only marks, mark=*, blue] coordinates {
      (1,2) (2,3) (3,2.5) (4,4) (5,3.5)
    };
    \addplot[only marks, mark=square*, red] coordinates {
      (1.5,1.5) (2.5,2.5) (3.5,3) (4.5,2)
    };
    \legend{Set A, Set B}
  \end{axis}
\end{tikzpicture}