Learn Icelandic: Þessi bíll er minn.

The word for "this" changes to match the gender of the noun it points to. Because bíll (car) is a masculine noun, we must use the masculine form þessi. If we were talking about a neuter noun like hús (house), we would use þetta.

Why is the word for "mine" minn and not mitt?

Just like the word for "this", possessive words like "my" or "mine" must match the gender of the noun they describe. Since bíll is masculine, we use the masculine form minn.

Why doesn't bíll have the word "the" attached to the end of it?

In Icelandic, when you use a pointing word like þessi directly in front of a noun, the noun usually stays in its basic, indefinite form without the attached "the". So we say þessi bíll (this car), not þessi bíllinn.

How would I say "This is my car" instead of "This car is mine"?

To say "This is my car", you would use þetta as a general introductory word: Þetta er bíllinn minn. Notice how the structure changes, and bíll now takes the attached "the" ending because the possessive word comes after it.