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It should be in Applications folder. In Finder, click on Go menu and select Applications. This will open Applications folder. Or in Finder, press Command, Shift and A and this will open Applications folder. You will find Safari application there. Just click and drag it to dock and it will be placed there.
Or double click on it to open it. Then right click or control + click on the Safari icon on dock, select Options and enable Keep in Dock option.
Please let me know if that didn't work, so I will continue to help you