Kile supports user defined lists of abbreviations, which are replaced on demand by longer text strings. Look at Settings->Configure Kile...->Kile+Complete to configure one or more of theses lists. For the example given here, the abbreviation list in example.cwl must be chosen. In this file you will find for example the entry L=\LaTeX for example.

For example, type only the letter L. Now invoke the abbreviation mode of word completion with Edit->Complete->Abbreviation or keyboard shortcut Ctrl-Alt-Space, and the letter L is replaced by the string \LaTeX.