The correct choice between "safe travel" and "safe travels" depends on context, but "safe travels" is more commonly used and generally preferred.
"Safe travels" is a plural phrase, often used as a friendly, idiomatic farewell—like "Have safe travels!"—implying multiple aspects or stages of a journey.
"Safe travel," in contrast, is singular and grammatically correct but less common; it might appear in formal writing or specific phrases like "Wishing you safe travel." For example, you’d say, "Safe travels on your trip!" rather than "Safe travel on your trip!" because the plural feels more natural in casual or heartfelt expressions.
Stick with "safe travels" for most situations—it’s widely accepted and sounds right to native speakers!