Learn Spanish (Latin America): Esa palabra es nueva.

In Spanish, words for 'that' must match the gender of the noun they point to. Since palabra (word) is feminine, you use the feminine form Esa. The masculine form Ese is used for masculine nouns.

Why is the verb es used here instead of está?

We use es (which comes from the verb ser) to talk about basic characteristics and traits. Describing a word as 'new' tells us what kind of word it is, which counts as a characteristic, so we use es. We use está for temporary states or locations.

Why does nueva end in an a?

Describing words (adjectives) have to match the noun's gender. Because palabra is a feminine noun, the word for 'new' changes from the masculine nuevo to the feminine nueva.

How would I ask 'What is that word?' using the question words from this lesson?

You would say ¿Qué es esa palabra? to ask for a definition or explanation. You use the question word qué (what) right before the verb es, and since it is a question, you must remember to add an accent mark over the e.