As you may remember from your studies of English, a verb is a word that expresses action or existence. Korean verbs not only expresss action (to walk) and existence (to be), but also express description (to be interesting; to be good).
For the regular verbs in English, which are few and far between, you take the verb as you find it in the dictionary and add endings and helping verbs as appropriate:
|He/she present form:||walks|
|Progressive form:||is walking|
Almost all Korean verbs are regular, and they use a similar “stems and pieces” approach.