documentclass{article}
usepackage[many]{tcolorbox}
usepackage{lipsum}

newtcolorbox{learn}{
breakable,
enhanced,
arc=0pt,
outer arc=0pt,
colframe=red,
colback=red!05,
overlay unbroken and first={
  node[draw=red,fill=red,rotate=90,anchor=south east,text=white,font=bfseries]
   at (frame.north west)
  {Learn This};
  }
}

begin{document}

lipsum[4]
begin{learn}
lipsum[4]
end{learn}

end{document}

tikz-pgf