Pre–fix comes from the Latin praefigere and means:

A unit placed before a base.
Bases can be nouns, adjectives or verbs.

An example of a prefix before a noun is the negation through un–:
so that a Tat (deed) turns into an Untat (misdeed) and
Glück (good luck) becomes Unglück (bad luck)…

An example for a prefix before adjectives is the negation with miss–:
verständlich (understandable) becomes missverständlich (missleading).

The prefixes un–,  miss– and ko– can be found in nouns, adjectives as well as in verbs:

das Unglück – unglücklich – verunglücken
die Missgunst – missgünstig – missgönnen
die Kooperation – kooperativ – kooperieren

An example of a prefix used for forming verbs is: ver–, for instance in

verkaufen (to sell base verb: kaufen to buy)
vergolden  (to gild base noun: das Gold the gold)
verdeutlichen (to clarify base adjective: deutlich clear)

The base by itself often makes no sense or has nothing to do with the new meaning:
*gessen from vergessen does not exist and versuchen cannot be derived from suchen …

For the sake of effective learning it would at any rate make good sense to learn along as you go the parts of speech combinable with a prefix:

der Verkauf, verkaufen, verkäuflich!

The opposite of the prefix is the suffix: The former stands pre– i.e. «before” the base, the latter after it, e.g. the adjective suffix –bar in wunderbar.

One thing is certain: The part played by prefixes and suffixes in German word formation is not at all insignificant. This is revealed by glancing at any German dictionary, at the very latest from the word compostions with ab– onwards …

from abfahren (to leave) through ablehnen (to refuse) to ‘abwarten und Tee trinken’ (let’s wait and see) …

@ ..….…. bine -))):-