If yellow is an adjective what and?

You're close! While "yellow" can be used as an adjective (describing a noun), "and" isn't a word that completes the sentence.

To make a complete sentence, you'd need to provide a noun that the adjective "yellow" describes. For example:

* The yellow car

* A yellow flower

* The yellow sun

Do you have a particular noun in mind? Let me know, and I can help you complete the sentence!