kerning is the spacing between individual letters in a sentence as opposed to leading (the spacing between lines). because kerning involves letters being pushed further together or apart than usual, it can result in one word being misread as another (e.g. the word "kerning" being read as "keming" where the "m" is made up of an "r" and "n" pushed together).
side note: if you're interested in seeing some hilarious examples of this, r/keming on reddit has a variety of funny examples.
