Learn Romanian: Câinele doarme pe iarba verde. - The dog sleeps on the green grass.

In Romanian, the word for "the" (the definite article) is attached to the end of the noun instead of coming before it as a separate word. For masculine nouns that end in -e, like câine, you add the ending -le. So, câine means dog, and câinele means the dog.

The basic word for grass is iarbă. Why does it end with an -a instead of an -ă here?

This is another example of the Romanian "the" attaching to the end of a noun. For feminine nouns that end in -ă, like iarbă, you drop the -ă and replace it with -a. Therefore, iarbă (grass) becomes iarba (the grass).

Why does the sentence say iarba verde instead of verde iarba?

In English, descriptive adjectives come before the noun (green grass). In Romanian, the rule is usually the opposite: the adjective comes immediately after the noun it describes. So, you literally say "the grass green".

Grass (iarbă) is a feminine noun. Does the adjective verde change its ending if it describes a masculine noun?

No, it stays exactly the same! Adjectives that end in -e in their base form (like verde) are identical for both masculine and feminine singular nouns. It will only change if you are talking about multiple things (the plural form is verzi).