Learn Spanish (Spain): El hombre es alto y la mujer es baja. - The man is tall and the woman is short.

In Spanish, adjectives (describing words) have to match the gender of the person or thing they describe. Hombre (man) is masculine, so it takes the masculine ending -o to make alto. Mujer (woman) is feminine, so it takes the feminine ending -a to make baja.

If I wanted to talk about two tall men, how would alto change in this sentence?

You would add an -s to make it plural! The phrase would become los hombres son altos. Adjectives must match both the gender (masculine or feminine) and the number (singular or plural) of the noun.

Why do we use es (from the verb ser) instead of está for their height?

We use ser (which becomes es for one person) for physical descriptions and permanent traits. Even though people can grow over time, height is considered a core characteristic of a person in Spanish, not a temporary state like being tired or happy.

I've seen bajo used to mean low. Does it also mean short?

Yes! When talking about objects or buildings, alto means high and bajo means low. But when describing people, as in this sentence, they are used to mean tall and short.