The English language uses many processes of word formation, so probably your question refers to the main processes, plural. These include compounding, blending and the related analogy, and acronyms. Compounding is the combination of two nouns to form another. Usually it is written as a single word. Example: “carport.”
Blending is the combination of parts of two words to create a new word with a different meaning, or coinage. One author who notably coined many words is Lewis Carroll, especially in his poem “Jabberwocky.” Example: “Slithy” usually considered to blend “slimy” and “lithe.” Others pronounce it with a short I, however, claiming “slither” is a component.
Analogy substitutes a portion of a term for one related to it, such as “mocktail” for “cocktail.”
Acronyms are sets of initials, and they then are used as words. Example: “scuba,” an acronym for “self-contained underwater breathing apparatus.”