Yes, you are able to change every single word on your marketplace page, even text or words inside the buttons or headers, as well as text and words in your buyer and seller portal. This enables you to customise the words in your header or buttons on your page to be contextualised to the business and audience you are engaging with, leading to an enhanced user experience.
This can be done on the Admin portal, via Content > Language > Edit Text.
For instance, you can change the "BE A SELLER" text in the header to "Sell with us!" by visiting the Admin Pages > Marketplace Header/Footer tab in the Edit Text page.
The changes will be reflected on your marketplace immediately upon saving: