Hi,
If you want to use spanish interface use https://help.invoiceocean.com/864657-Changing-the-interface-language
Or issue a billingual invoice https://help.invoiceocean.com/497344-How-to-issue-a-bilingual-invoice-
Change e-mail language https://help.invoiceocean.com/476288-Separate-email-languages-and-templates-for-departments
Cheers,
Malgorzata Kozicka