Learn Finnish: He siirsivät jokaisen trukkilavan paitsi tuota vanhaa erää. - They moved every pallet except that old batch.

The main object takes the genitive-accusative because the action of moving was fully completed (making it a total object). However, the word paitsi (except) acts as a preposition that strictly requires the partitive case for whatever follows it, regardless of the main object's case.

Does erää come from the pronoun eräs (a certain)?

No, it is the partitive form of the noun erä, which translates to a batch, lot, installment, or even a round in sports. Here it refers to a physical batch of goods. It is easy to confuse with the pronoun eräs, but they are different words.

How does the compound word trukkilavan break down?

It is the genitive-accusative form of trukkilava (shipping pallet). This is made up of trukki (forklift) and lava (platform, stage, or pallet). Literally, it means a forklift platform.

Why use the pronoun tuota instead of sitä here?

Tuota is the partitive of tuo (that), which is used to physically point out something distinct or slightly further away. While sitä (from se) can also mean 'that', it is often used for abstract references or as a generic 'it'. Tuota emphasizes distinguishing this specific old batch from the others.