Learn Portuguese (Portugal): A menina é uma criança adorável.

It comes from the verb adorar (to adore or to love). By dropping the final -r and adding the suffix -vel, we create an adjective that means capable of being adored. This is a highly regular way to turn verbs into adjectives in Portuguese.

If we were talking about two adorable children, how does the ending of adorável change?

To make words ending in -vel plural, you drop the -l and add -is. So, adorável becomes adoráveis. For example, the plural sentence would end with crianças adoráveis.

Do I need to change adorável to make it masculine if I talk about a boy?

No, adjectives created with the -vel suffix are gender-neutral. They have the exact same form for both masculine and feminine nouns. Whether you describe um menino (a boy) or uma criança (a child), the adjective stays adorável.

Why do we use é here instead of está?

We use é, from the verb ser, for permanent or inherent characteristics. Describing someone as an adorable child expresses a fundamental personality trait rather than a temporary mood or state, which would require the verb estar.