Learn German: Lass uns das Holz für die Leiter sägen! - Let's saw the wood for the ladder!

We use Lass uns because the speaker is talking to exactly one person informally, like a friend. If you were making this suggestion to two or more friends, you would say Lasst uns das Holz... sägen!. For formal situations, you would use Lassen Sie uns.

Why does the verb sägen go at the very end of the sentence?

The Lass uns construction works a lot like modal verbs in German. The conjugated command word (Lass) takes the standard position near the beginning, and the main action verb in its infinitive form (sägen) gets pushed to the very end of the clause.

Wait, isn't Leiter a masculine noun meaning the manager or leader?

It depends on the gender! The word der Leiter (masculine) means the male leader or manager. However, die Leiter (feminine) means the ladder. Since they are sawing wood in this sentence, they are definitely talking about the feminine noun.

Why is it für die Leiter? Does the preposition für change the case?

Yes, the preposition für always forces the following noun phrase into the accusative case. Because Leiter is a feminine noun here, its accusative article is die, which conveniently looks exactly the same as its nominative dictionary form.