Error in xcode "Type 'RoundedRectangle.Type' cannot conform to 'View'"?

Question

Swift

import SwiftUI

struct ContentView: View {
    var body: some View {
        HStack {
            CardView ()
            CardView ()
            CardView ()
            CardView ()
            CardView ()
      
        }
            .padding(.horizontal)
            .foregroundColor(/*@[email protected]*/.red/*@[email protected]*/)
    }
}
    struct CardView: View {
        var body: some View {
            ZStack {
            RoundedRectangle(cornerRadius:20).stroke(lineWidth:3)
            Text("Hello, world")
        }
     }
}