Here is a solution based on Jake's answer here. The outer tikzpicture defines the interesting places we want to point to as nodes with the coordinate shape, called below e and below m in my examples. It uses the remember picture option to make these coordinates visible from outside the tikzpicture. The pictures that draw the arrows use the options remember picture (to be able to access the destination nodes by name, which are in another picture) and overlay (so as not to take any space on the page as far as TeX is concerned).
Of course, once you have found good coordinates for the destination points of the arrows you want to draw (which I call the “interesting places”), you should comment out or remove the code that draws the grid and the associated graduations—these are only here to help you find suitable coordinates for the “interesting places”.
First example
The following example uses text that is boxed inside a node with shape rounded rectangle as the source of the arrow—since the question mentions boxed text. rounded rectangle comes from the shapes.misc TikZ library.
\documentclass{beamer}
\usetheme{Madrid}
\usepackage{graphicx}
\usepackage{tikz}
\usetikzlibrary{positioning, shapes.misc}
\begin{document}
\begin{frame}
\frametitle{The frame title}
\begin{figure}[H]
\begin{tikzpicture}[remember picture]
\node[anchor=south west, inner sep=0] (image) at (0,0)
{\includegraphics[width=0.6\linewidth, height=3cm]{example-image}};
\begin{scope}[x={(image.south east)}, y={(image.north west)},
every node/.style={font=\tiny}]
\draw[help lines, xstep=.1, ystep=.1] (0,0) grid (1,1);
\foreach \x in {0,1,...,9}
{ \node [anchor=north] at (\x/10,0) {0.\x}; }
\foreach \y in {0,1,...,9}
{ \node [anchor=east] at (0,\y/10) {0.\y}; }
% Define nodes here for the “interesting places” (i.e., where we
% want the arrows to point to).
\coordinate (below e) at (0.7,0.42);
\end{scope}
\end{tikzpicture}%
\begin{tikzpicture}[remember picture, overlay]
\draw node[rounded rectangle, draw=gray!80, fill=gray!10,
right=0.8em of image.east] (box) {Boxed text}
(box) [->, red!60!black] to[out=-150, in=-70] (below e);
\end{tikzpicture}
\end{figure}
This is below the picture.
\end{frame}
\end{document}
Second example
The following example uses a different technique: the arrows can start from anywhere you wish in the beamer slide. We draw two arrows, one that starts after a word or punctuation sign in a paragraph, and one that starts in the margin before the beginning of a paragraph (note that it is also possible, using \vadjust, to make an arrow start in the margin at the beginning or end of a line containing a particular word in the middle of a paragraph—that's essentially exercise 14.28 of the TeXbook, if you abstract the TikZ-based implementation).
\documentclass{beamer}
\usetheme{Madrid}
\usepackage{graphicx}
\usepackage{tikz}
\begin{document}
\begin{frame}
\frametitle{The frame title}
\begin{figure}[H]
\begin{tikzpicture}[remember picture]
\node[anchor=south west, inner sep=0] (image) at (0,0)
{\includegraphics[width=0.6\linewidth, height=3cm]{example-image}};
\begin{scope}[x={(image.south east)}, y={(image.north west)},
every node/.style={font=\tiny}]
\draw[help lines, xstep=.1, ystep=.1] (0,0) grid (1,1);
\foreach \x in {0,1,...,9}
{ \node [anchor=north] at (\x/10,0) {0.\x}; }
\foreach \y in {0,1,...,9}
{ \node [anchor=east] at (0,\y/10) {0.\y}; }
% Define nodes for interesting places (here: where we want the
% arrows to point to).
\coordinate (below e) at (0.7,0.42);
\coordinate (below m) at (0.4,0.42);
\end{scope}
\end{tikzpicture}
\end{figure}
This is below the picture. Here is an arrow pointing below the ``e'' of
our image: % one space token
\begin{tikzpicture}[remember picture, overlay, baseline=-0.5ex]]
\draw[->, red!80!black] (0,0) to[out=0, in=-120] (below e);
\end{tikzpicture}
\hspace*{-0.1em}% we'll start the second arrow in the left margin
\begin{tikzpicture}[remember picture, overlay, baseline=-0.7ex]]
\draw[->, blue!80!black] (0,0) to[out=180, in=-95] ++(-0.6em,5ex)
to[out=85, in=-90] (below m);
\end{tikzpicture}%
\hspace{0.1em}%
A second arrow pointing below the ``m''.
\end{frame}
\end{document}
tikzmark. Or if your plot can be exported to TikZ, you can add arrows directly withouttikzmark. That is all what I can say for now, as I can't reproduce your plot. – fractal Dec 21 '19 at 12:29tikzpicture, or define coordinates in the wrapped picture (possibly using\tikzmark) for the “arrival points” of your arrows. In the latter case, passremember pictureto thetikzpicturecontaining the image and destination coordinates to make them visible from outside thetikzpicture, andoverlayfor thetikzpicturecontaining the arrows (for the bb). – frougon Dec 21 '19 at 12:59