Hertz measures cycles per second - one Hertz is one cycle per second. Unlike gauss that is a measurement unit for the strenght of a specific thing (an electromagnetic field), hertz is a generic frequency measurement.
Prepend is a word that means to attach content as a prefix. It is often used in different kinds of programming and in automated processes. Some prepending is done manually as a user. For example, a prepend command could be used in a scripting language that a programmer would enter into a certain function or code module. It would add certain characters of text to the beginning of some variable or object.
Preposition(noun) a word employed to connect a noun or a pronoun, in an adjectival or adverbial sense, with some other word; a particle used with a noun or pronoun (in English always in the objective case) to make a phrase limiting some other word; -- so called because usually placed before the word with which it is phrased; as, a bridge of iron; he ...