In the Parts of Speech lesson, I learned how each word in a sentence has a role. One sentence that I found helpful was "Nouns name people, places, things, or ideas." Another one was "Verbs express actions or states of being."
In the first sentence:
Nouns - noun
name - verb
people, places, things, ideas - nouns
or - conjunction
In the second sentence:
Verbs - noun
express - verb
actions, states - nouns
or - conjunction
of - preposition
being - verb
I think knowing parts of speech makes it easier to understand how sentences work and how words fit together.