These are the most visible default settings on your front-end.
PrestaShop is able to work with many languages, both on the front-office and the back-office. Each text-field is accompanied with a flag icon, which indicates the current language, and which you can click in order to choose another language in which to write that field's content.
By default, PrestaShop is only installed with one language: English. You can easily enable more languages: open the "Localization" menu, choose the "Languages" item, and the page opens, with a table of all 5 available languages: English, German, Spanish, French, Italian. The currently enabled language(s) have green check mark, while the others have a red "X". Click on any of the red "X" in order to enable its language.
You can enable as many languages as you feel your shop needs, but be aware that this will means that you will have to create content for all of the available languages: product name, description, tags; category name and description; static content (CMS pages); etc.
Only 5 languages are available by default. You can add more if you need. Find out how in the "Managing Localization" chapter.
Should you have people helping you with your shop, be they your spouse, friends or paid employees, you should make sure to create an employee account for each of them, if only to know who is responsible for which action. The other advantage is that you can give them specific profiles and specific access rights to the administration pages: for instance, you might not want everyone to have access to your statistics, your invoices or your payment settings.