You can offer your store in English, Spanish, French, Italian, German, Indonesian and many other languages. But currently, it is only possible to offer your branchbob store in one language at a time. For this reason, your customers don't have the opportunity to choose between those languages. But a possible option is to open up two similar shops, for example, one in English, one in German. If you are linking the shops mutually in the cover page text saying that the German/English shop is available under the following link, your customers can choose their favourite option. Good to know is that self-entered product descriptions and texts are not automatically being translated with switching the language (this just counts for buttons and tabs).
All languages can be selected under "General" > "Language" in "Store Settings".