Learn Icelandic: Lesið textann minn á töflunni!

Lesið is a plural command. You use the -ið ending on the verb when you are telling two or more people to do something. If you were only telling one person to read, you would use the singular command lestu.

Why is the word for text textann here?

The dictionary form is the masculine word texti. Because the text is the direct object (the thing being read), it changes to the accusative case. We also need to attach the word for 'the' to the end of it, which gives us the ending -nn, making the final word textann.

Why is the word for 'my' minn in this sentence?

Possessive words like 'my' have to match the noun they describe. Because textann is a masculine, singular word in the accusative case, the word for 'my' must take the exact matching form minn.

Why does the word for board change to töflunni?

The dictionary form is the feminine word tafla (board). The preposition á (on) causes the noun after it to change to the dative case when describing a fixed location. The dative form of tafla is töflu, and when we add the dative feminine ending for 'the' (-nni), we get töflunni.