Morphemes can be lexical or grammatical. Lexical morphemes are the "meaty" part of a word that has the clear meaning. Because they have their own meaning, they can stand by themselves. Grammatical morphemes have a job rather than a meaning. It is difficult to say what they mean but easier to say what they do.
Happy -> happily (here the extra morpheme makes the word an adverb)
Dog -> dogs (here the extra morpheme makes the word plural)
Child -> children (here the extra morpheme makes the word plural too)
Wait -> WAIT-FOR-AGES (here the extra morpheme adds the idea of “a long time” to the action).