Learn Romanian: Vremea este foarte frumoasă. - The weather is very beautiful.

In Romanian, the equivalent of the English word the is attached to the end of the noun. The base word is vreme (weather), and adding -a gives you vremea (the weather).

I sometimes see e used to mean is. Can I use e instead of este in this sentence?

Yes, you can perfectly say Vremea e foarte frumoasă. Both este and e mean is. Este is the full written form, while e is a shorter version that is extremely common in spoken Romanian.

Why is the word for beautiful written as frumoasă instead of frumos?

Romanian adjectives change to match the noun they describe. Because vremea is a feminine noun, you must use the feminine singular form frumoasă instead of the masculine form frumos.

Does the word foarte change depending on the noun, just like the adjective did?

No, foarte (very) never changes its form. It goes directly before the adjective and stays exactly the same whether the noun is masculine, feminine, singular, or plural.