I’m back from my motorcycle trip to Florida. I found some mistakes on signs at the Kennedy Space Center! The trip was not your everyday bike ride—it lasted more than 3200 miles, not something you would do every day.
Everyday is an adjective. It means common, or ordinary. A compound adjective actually. It goes with nouns, so you might say “an everyday restaurant.”
Every day is an adverb phrase. You’re saying when (how often) something happens. Use it the way you would any adverb. “Every day we go for a walk.” “Drink green tea every day.”