The answers to this useful question explain how to show the encoding of a TeX font. And this is the default encoding used in the default TeX font, cmr10:
What was the strange diagonal dash character at '040 intended for? It appears to be not quite an acute accent (which is '023). Does it combine with something else?
It is for the Polish ł and Ł (l and L with stroke). Plain TeX contains \def\l{\char32l}. And LaTeX (OT1enc.def) defines
\DeclareTextCommand{\l}{OT1}
{\hmode@bgroup\@xxxii l\egroup}
where \@xxxii stands for char32.
\documentclass{article}
\begin{document}
\char32l
\l
\end{document}
From plain.tex:
663 \def\l{\char32l}
664 \def\L{\leavevmode\setbox0\hbox{L}\hbox to\wd0{\hss\char32L}}
The glyph is used just for the Polish “suppressed l”. The support for Polish in Computer Modern is not complete, as the ogonek is missing, but, apparently, Knuth didn't need to typeset Polish names sporting the ogonek.
