import SwiftUI
import PlaygroundSupport
import Foundation

struct ContentView: View {
    @State var minutesOfTraining = 10
    var body: some View {
        VStack {
            HStack {
                Button(action: {
                    $minutesOfTraining -= 1
                }) {
                    Text("-")
                }

                Button(action: {
                    $minutesOfTraining += 1
                }) {
                    Text("+")
                }
            }
            Text(minutesOfTraining)
        }
    }
}

PlaygroundPage.current.setLiveView(ContentView())

Whats wrong here?

Whats wrong here?

Two things:

1. You don't need to use $ in your action closures. $ applied to an @State variable indicates you want to access the Binding, not the variable itself. Just use minutesOfTraining if you want to increment that variable.
2. minutesOfTraining is an Int, so you can't pass it directly to a Text element, which has no applicable initializer. Instead, you need to use something like Text("\(minutesOfTraining)")