In Safari, tap the "More Options" icon (three horizontal dots) located in the address bar to open the settings menu.
From the menu, select "Manage Extensions" to open the extensions settings.
In the extensions list, you'll find various Ad Blocker options, such as AdBlock, Adult Content, Tracking and others.
Switch on the toggle next to the Ad Blocker extensions you want to enable. A green toggle means the extension is active.