When designing a TabView you have the option to add an icon for each tab using a system image, using the systemImage parameter to Label:

TabView {
    Text("First")
        .tabItem {
            Label("First", systemImage: "tray")
        }
}

In this case we use tray.

How do you find out which other icons you can use?

Apple created an app for this, called SF Symbols. Download it from https://developer.apple.com/design/downloads/SF-Symbols.dmg, install it on your Mac and once you open it, you can browse over 1500 symbols and see their name:

Lessons in this unit:

0:	Introduction
1:	NavigationView
2:	TabView
3:	▶︎ SF Symbols
4:	Forms
5:	TextField in Forms
6:	Toggle in Forms
7:	Slider in Forms
8:	Stepper in Forms
9:	Picker in Forms
10:	DatePicker in Forms