Learn Russian: Страна большая и красивая.

In Russian, the present tense of the verb "to be" (am, is, are) is normally left out. You simply put the subject (страна) and the adjectives describing it (большая и красивая) together.

Why do the words большая and красивая both end in -ая?

Adjectives in Russian must match the gender of the noun they describe. Because страна is a feminine noun (you can tell because it ends in -а), the adjectives take the standard feminine ending -ая.

Could I put the adjectives before the noun, like "Большая и красивая страна"?

Yes, but it changes the meaning slightly. Большая и красивая страна means "A big and beautiful country." By putting the noun first, this sentence means "The country IS big and beautiful," making the adjectives the main point.

Why do we use и for "and" here instead of а?

The word и is used to simply add things together, like joining two qualities of the country. The word а is used to show contrast (meaning "but" or "whereas"). Since "big" and "beautiful" are just two facts being listed, и is correct.