One coding problem I am facing, As I am beginner so I don't know how to do it

Welcome to the forum.

This is a part of Apple sample project, isn't it ?

Your post is just some code, with no question. So please, explain what it is you don't succeed in doing.

Note: when you post code, you should use the code formatter tool:

import SwiftUI
struct CardView: View {
    let scrum: DailyScrum
    var body: some View {
        VStack(alignment: .leading) {
            Text(scrum.title)
                .font(.headline)
            Spacer()
            HStack{
                Label("\(scrum.attendees.count)", systemImage: "person.3")
                Spacer()
                Label("\(scrum.lengthInMinutes)", systemImage: "clock")
                    .labelStyle(.trailingIcon)
            }
            .font(.caption)
        }
        .padding()
        .foregroundColor(scrum.theme.accentColor)
    }
}
//#Preview { // CardView(scrum: <#T##DailyScrum#>) //}
struct CardView_Preview: PreviewProvider{
    static var scrum = DailyScrum.sampleData[0]
    
    static var previews: some View {
        CardView(scrum: scrum)
            .background(scrum.theme.mainColor)
            .previewLayout(.fixed(width: 400, height: 60))
    }
}

I want to know how to convert this "PreviewProvider" into "#Preview" in this code

You should write:

#Preview { 
    var scrum = DailyScrum.sampleData[0]
    
    CardView(scrum: scrum)
            .background(scrum.theme.mainColor)
            .previewLayout(.fixed(width: 400, height: 60))
}