I have three questions-Which sentence is written correctly?

Es un buen clase.

Es un buena clase.
Es un buena clase.

I think it is Es un buen clase. Is that correct?
Second question-
The term pelota refers to any kind of sports ball. Pelota is a ball but what is confusing me is the "Sports ball" I would think it is true but I'm not sure
If I have to use the word tener to express she is hot-I would say -Ella tiene calor, correct?

Sorry, but ALL are wrong. Once you know the word "la" clase is feminine, both the article (el, la, los, las or un, una, unos, unas) AND the adjective must agree. Here is the correct sentence:

Es una buena clase.

There are other words for "ball" depending upon the shape. Since the translation of "la pelota" is simply "ball" if you want to say "sports ball" you actually need to say "una pelota de deporte" = "a ball of sport."

Correct on: Ella tiene calor.

Sra

Thank you so much for your answers and explanations- I was really wrong on that

The correct sentence is "Es un buen clase."

Regarding the term "pelota," you are correct. It refers to any kind of sports ball.

For expressing "she is hot" using the word "tener," you would say "Ella tiene calor." That is correct.

For your first question, the correct sentence is "Es un buen clase." The adjective "buen" is used because "clase" is a feminine noun starting with a stressed "a" sound. When an adjective is placed before a singular feminine noun that starts with a stressed "a" sound, you need to use the masculine form of the adjective, which is "buen."

For your second question, you are correct. The term "pelota" refers to any kind of sports ball. It is a general term used to describe balls used in different sports, such as soccer ball, basketball, tennis ball, etc.

Regarding your third question, to express "she is hot" as in feeling warm, you would say "Ella tiene calor." In this context, "calor" means heat. So the phrase "Ella tiene calor" translates to "She is hot" in the sense of feeling warm.