Can't type ' / ' (slash) after the letter ' l ' (ell) in Terminal, makes 'l' with stroke character 'ł'
This looks like the behavior of some very old Mac fonts (Palatino was one of them) where you could make the character l with stroke (used in Polish and elsewhere) by typing such a sequence.  Try changing your font.  If this is in fact the cause of the problem,  you should get rid of the font that does this, which should not be on any modern mac.