Action verbs can be used in BE + -ING (progressive tenses(:
Example:
My mother is cooking dinner now
'non action verbs' cannot be used in BE + -ING:
(They mean in progressive tenses)
ABSTRACT be, believe,know, need, understand, remember, think, imagine, forget, mean, exist...
FEELINGS like, dislike, love, hate, fear, envy, care...
SENSES hear, see, feel, smell, taste, sound, seem
BELONGINGS own, have, belong, possess
you can check book Understanding and Using English Grammar on page 16
there are more examples