Content Words and Function Words

Many English words describe things, actions, feelings etc. If we can see, smell, touch and do these things, actions, and feelings, we use content words.

Nouns, Verbs, Adjectives and Adverbs are content words. N, VB, ADJ and ADV are important words, so we make them easy to hear (they are very clear). When we speak English, N, VB, ADJ and ADV are LONG (Loooooong), LOUD (LOUD) and HEAVY (heavy).
Some words are NOT about things. These are not N, VB, ADJ and ADV.
These words are function words. Function words are not very important,
so we do not make them easy to hear (they are unclear).

In this sentence, the content words are in large, red, bold print, the function words are in smaller, green italic print.

Give me some money. My sister is hungry.