Learn Italian: La primavera è una bella stagione.

In Italian, you need to use a definite article (il, la, etc.) before the names of seasons when you are talking about them generally. While English just says "Spring is a beautiful season," Italian literally says "The spring is a beautiful season."

Stagione ends in -e. How can we tell if it's a masculine or feminine noun?

Nouns ending in -e can be either masculine or feminine, so you eventually have to learn the gender with the word. However, this sentence gives you three big clues: the feminine articles La and una, and the feminine adjective bella. They all change their endings to match the feminine noun stagione.

Why is bella placed before stagione? Don't Italian adjectives usually go after the noun?

Yes, most adjectives go after the noun in Italian. But a small group of very common adjectives, such as bello (beautiful), buono (good), grande (big), and piccolo (small), are exceptions. They usually come right before the noun they describe.