Using putty, Left and Right keys move cursor one word, instead of one char

I have looked for a solution to this OhMyZSH! problem for a few days now, but can’t find a solution.
Admittedly, I do not understand how zle really works, same for bindkey. Same goes for the way terminal emulators send “control sequences”, and what the “terminal type” means (xterm, versus xterm-256-color, and others). Same for the “Application mode”