What is the verb form of safe?

The plural for safe is safes.

This is in reference to the Word "safe" meaning a repository for one's valuables, e.g. a bank safe. "None of the safes were broken into."

The Word safe is also an adjective (safe, safer, safest). "Is this a safe website?"

In the English language, adjectives do not have a plural form.

"The kid is safe. The kids are safe."