Learn Finnish: Tuo lapiot ja ämpärit tänne! - Bring the shovels and buckets here!

This sentence has a plural total object. When an action applies to a specific, complete set of multiple things (like bringing the specific shovels and buckets), the object takes the plural nominative ending -t.

I learned that in commands, the object doesn't take an ending. Why do these have a -t ending?

That rule only applies to singular objects! If you were asking someone to bring one shovel, you would say Tuo lapio! (no ending). But for plural objects, the -t marker is always required, even in commands, so we know there is more than one.

How is the command Tuo formed from the verb tuoda (to bring)?

To make a singular command, you start with the 'minä' (I) form of the verb and drop the -n. 'I bring' is minä tuon. Drop the -n, and you get the command Tuo!

Why does the sentence use tänne for 'here' instead of täällä?

In Finnish, location words change depending on whether there is movement. Täällä means being statically in a location ('at here'), but bringing something involves movement towards a destination. Tänne means 'to here', which matches the movement of bringing the tools.