How am I supposed to know that this time "lisons" means "let's read"?
This sentence is formed with the imperative. it begins directly with the verb and there are no articles in front of the verb. :)
The first time, you won't know. But then you learn. It's quite a basic concept.
I suggest you read up on the imperative.
When there are no pronouns before a verb, it's usually the imperative.
Same as english when you order someone.