Learn Finnish: Naiset siivosivat pihan luudilla ja haravoilla. - The women cleaned the yard with brooms and rakes.

In addition to location (like pöydällä - on the table), the adessive case is used to express the instrument or tool you use to do an action. In Finnish, you do not use a separate preposition for "with" a tool; instead, luudilla ja haravoilla translates to "by means of brooms and rakes".

How do we get the form luudilla from the word luuta (broom)?

To make the adessive plural, you need the weak plural stem. The word luuta undergoes consonant gradation (the strong t weakens to d), and the final -a drops to make room for the plural marker -i-. This gives the stem luudi-. Finally, you add the adessive ending -lla, resulting in luudilla (with brooms).

Why does harava (rake) change to haravoilla instead of just "haravilla"?

For words ending in -a that have three or more syllables, the final -a usually changes to -o- before the plural -i- is added. Therefore, the plural stem of harava becomes haravoi-. Adding the adessive ending -lla gives you haravoilla.

Why is the yard (piha) written as pihan with an -n ending?